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1. l A p e i M i m E d Bv MIKE DALE Doing away with the throttle cable was just the beginning Electronic throttle control ETG has allowed engineers to add many other noteworthy vehicle systems and capabilities with more to follow t may well be that software integration of automotive electronic systems will turn out to be the most significant automotive tech nological development of this decade Origi nally electronic systems such as ABS H VAC and emissions were developed separately by those groups within each carmaker that were most responsible The brakes and suspension group worked on ABS while emissions and engine control issues were handled by powertrain people Software integration has brought these systems together The result is new interrelated technologies that produce better mileage safer cars and reduced emissons At the head of this trend as an enabling technolo gy is electronic throttle control ETC which is part of an industrywide response to calls for better fuel economy reduced emissions and a reduction pap in vehicular fatalities This story is ee fe Ae Not so much about hardware as Apes u P3 it is about software that uses gt E i ETC asan input and an actua f i tor to make the new technolo p gies possible Without ETC the planned ad vances in hybrid and diesel technology that are now right around the2. O Check bulletins and other service information No DTC D No Matching Intermittent Select the symptom Rafer tn dirtemiiient Symptom from symptom chart stone Develop diagnostics and follow pe from wiring chart recommendations theory DTC Stored Follow the designated DTC table to repair Vehicle operates as designed Explain operation to customer Find isolate the Re examine the problem Concern g Repair Resolve Verify fix Verify the Customer Concern Expanded Know how the vehicle systems operate the driving habits of the customer and the environmental driving conditions The figure on the next page shows a 2001 VW Passat Central Locking Module located in a pan below the driver s seat Mud and snow can leak into this box and short out the computer thus killing the communication with the Scan Tool At this time there is no TSB on this problem but you can find information on the problem by browsing the Internet Even though the Internet is a great resource for information you should take the time to make sure the information is accurate by checking other websites Note Bosch does not support promote or endorse any websites other than its own company website www Bosch com J393 Central control module for comfort system e in protective box floorpan cavity under driver s seat carpet Graphic captured from the Internet Perform published diagnostic system checks expanded Co
3. At the heart of the hybrid control sys tem described by F ord is the electronic throttle control system and its ability to accept driver input and then output a throttle angle position in keeping with the best interests of the whole system Its the integrated software of the trans mission and engine control systems that gives the system response To sum up what started out as a means of eliminating the mechanical connection between the throttle pedal and the engine has evolved and taken on a larger and far more important role By integrating the safety emissions and powertrain electronic subsystems it has become possible to implement new yiEw technologies that could not have been implemented independently E lectronic throttle control is a mandatory element of these advanced systems M Visit www motor comto download a free copy of this article If your customers could see what they re breathing they d MIST right away kal ami bacteria Teume Growin mede the Anton sytem ol a Dwo yesx old vehicle POW with a cabin air Gite 1 877 776 8486 us through www uview com i MIST In Car Air Quality Service Circle 31 July 2007 MOTOR 51 BOSCH OBD II Network Diagnostics Diagnostics Using OBD Il NOTES Data Bus Communication Networks Overview Vehicle On Board Control Modules are changing the automotive industry in two related areas The first area concerns the expansion and use of multiple on b
4. ment in 0 to 60 times Unlike conven tional transmissions with their ratio spread of approximately 4 0 to 1 0 the new H ydramatic F ord transmission has a wider overall ratio of 6 0 to 1 0 Elec tronic throttle control is an integral part of the improvements in both fuel econ omy and acceleration H aving so many gears requires some adaptations Toyotas eight speed trans mission for example has a software provision to skip gears during decelera tion to make the downshifting smoother and less apparent to the driver The ETC system smoothes the shift perfor mance between gears by adjusting the throttle opening at the shift point Pro grammed steps in the ETC system can be used to give the driver the feel of a conventional transmission so the CVT doesn t feel odd D riveline management software is used to select the combination of engine output and gear ratios that will deliver the needed torque in the most efficient way T he software is capable of reducing the torque input to the transmission during the shift sequence to reduce me chanical shock to the drivetrain This driveline management software is espe cially important for on demand AWD T he shift from two wheel to four wheel drive must be controlled to avoid torque bumps and other interactions between the drive wheels Displacement Reduction for Light L oad Conditions GM Chrysler and others have implemented variable displacement strategies GM 55 D isplace m
5. Another approach is through variable valve timing VVT systems offer varying degrees of control based on system com plexity limits E arly intake valve clos ing EIVC late intake valve opening LI VO late intake valve closing LIVC and fully variable valve lift strategies have demonstrated reduced pumping losses and improved fuel economy GM has tried the EIVC strategy which uses the variable intake valve closing and intake valve lift control to unthrottle the engine at part load and light load operating conditions H ere the intake valve duration and lift are significantly reduced to control airflow into the engine allowing it to operate at higher intake manifold pressures with the potential to fully unthrottle the engine under all operating conditions Electronic or hydraulic valve actua tion solenoids under the direction of software controlled cam profiles may someday offer even greater flexibility T hese systems have been talked about and demonstrated Renault had one in a Formula One racer a while back with a keeping with the results of the computer s algorithm 17 000 rpm redline So far the software cam has not appeared in a production vehicle due to the dynamic complexity of landing the valve back on its seat without noise The actuators shown so far are also bulky and expensive in com parison to mechanical actuation According to GM the downside to these various VVT strategies for produc tion engines is that
6. Line Volkswagen Passat showing four different networks CAN A Comfort amp Convenience Systems e low med speed data of 1k bit s to 20k bit s No real time requirements Single wire Cost effective Uses various protocols CAN D Multimedia e Real time data 1M 400M bit sec e Fiber optic network protocol with capacity for high volume streaming include automotive multimedia and personal computer networking The graphic on the next page shows a fiber optic CAN D network Page 11 OBD II Network Diagnostics NOTES Page 12 BOSCH A Growing List of CAN Applications Below is a list of some vehicles that are currently in CAN compliance CAN compliant means that the CAN network broadcasts diagnostic information to the scan tool Pins 6 amp 14 or 3 amp 11 in CAN protocol language Many scan tools have to be updated with CAN module adapters to communicate at the higher baud rates that CAN systems produce 2003 Ford Excursion 2003 Ford F 250 and F 350 2003 Ford Focus and Thunderbird 2003 General Motors Saturn ION 2003 Lincoln LS 2003 Mazda 6 2003 Saab 9 3 2004 Buick Rendezvous 2004 Cadillac CTS XLR and SRX 2004 Dodge Durango 2004 Ford Explorer 2004 Ford F 150 E 250 and E 350 2004 Ford Taurus 2004 Lexus LS430 2004 Mercury Mountaineer 2004 Mercury Sable 2004 Mazda 3 and RX 8 2004 Toyota Prius 2004 Volvo S40 2005 Audi A4 and A6 2005 Chevrolet Equinox 2005 Chevrolet Trailblazer EXT 2005 Dodge Dakot
7. corner would not be possible Cur rent advances such as electronic stability control ESC expected to save thousands of lives per year would simply not be possible without E TC Best yet q ETC reduces cost and complexity for carmakers by integrating formerly stand alone features such as idle control cruise control and throttle control into a sin gle mostly software based system This latest version of electronic throttle control should not be confused with the earlier stand alone S systems that replaced the mechanical link between the driver and the engine n these new systems the output of the pedal sensor is an input not only to the engine control system but to the software system as aS whole As such pedal angle becomes a valuable input z to other electronic control systems The algorithms that control the ABS ESC cruise control HVAC and d other system functions all use pedal angle data in the decision making process The throttle angle that re sults is not only what the driver wants but what the systems needs for correct and safe operation In these new generation ETC systems the accel erator pedal module becomes a two way device Its accepts information about desired engine output E from the driver plus it can feed back tactile informa tion to the driver as a warning that the selected en gine output is either wrong or dangerous Jupiter Im Harold Photoillustr July2007 MOTOR 41 ELECTR
8. of power output The downside to this is that having partial pressure in the intake manifold wastes energy As the piston moves downward on the intake stroke normal pressure below it and partial vacuum above it cause drag on the rotation of the crankshaft These pumping losses occur during most engine operating conditions asthe throttle is seldom truly wide open Diesel engines are known to be ap proximately 2596 more efficient than gasoline engines According to Toyota one reason is that the diesel engine uses no throttle and thus suffers reduced pumping losses n gasoline engines the throttle related losses are believed to be in the range of 7 to 10 Diesel en gines are also more efficient due to their higher compression ratio GM says that it s difficult to achieve all of the design goals of better fuel economy reduced emissions and driver safety at the same time Typically in a fixed valve timing engine best power has be traded off against other desirable elements such as torque idle stability and fuel economy 44 MOTOR July 2007 There are other approaches that try to deal with the issue of the throttle related partial power problem Gasoline direct injection is an approach to im proving efficiency by calibrating each combustion event to the needed power requirements The direct injection sys tem controls engine power by injecting only that amount of fuel needed to pro duce the desired engine power output
9. ESC system runs an algorithm that determines if the requested engine out put is safe When it s advisable the out put from the system can be a throttle an gle command that s not what the driver requested When theres a possible loss of traction and or steering control the E SC system can overrule driver input to reduce throttle angle and engine power Electronic throttle control can also be used to protect the engine driveline and tires from operation that may cause excess wear or damage Rev limiting can be accomplished in software by governing the throttle angle rather than cutting off fuel or ignition This results in a much smoother limiting that does not cause the driver to sense that the engine has cut out as can be the case with ignition and fuel based limiter sys tems Rental car companies have The stepper motor positions the throttle plate P d 4 zi z i P zl i IET Lo TEL ET hi i Atalet Pean Coe po d i Amh The dual and offset outputs from the pedal angle sensor area form of redundancy according to the results of the computer s throttle position algorithm The gear train increases the resolution so the plate can be set with high accuracy pushed for rev limiters as a way of pro tecting their assets from drivers who don t care how hard they push a vehicle simply because they don t own it Using ETC to Enable Other Technologies GM 5 Vortec 5 3L V8 uses Active Fuel M anagement AFM
10. ETC systems is the above mentioned variable displacement Photo courtesy Abletronik strategies Cadillac s first attempt at vari able displacement V 8 6 4 in the early 80s foundered at the time for a variety of reasons including driver dissatisfac tion with how the engine felt as it dropped or picked up displacement ETC with its computer control is able to automatically make the throttle angle changes needed so the change is seam less to the driver Another benefit of ETC according to GM is the ability to modify vehicle response to a change in pedal angle po sition Consumer research shows that vehicle response to accelerator inputs greatly affects a driver s overall satisfac tion with the vehicle The response of the vehicle to the first 20mm 8 in of throttle movement may be more impor tant than the actual 0 60 acceleration time Vehicle Safety E lectronic stability control is probably the most significant safety development since the invention of the seat belt By federal requirement and automaker cooperation this system will be standard on all vehicles by 2010 The hope is that as many as 10 000 lives per year will be saved To function as it does ESC dependson ETC E lectronic stability control systems are an integration of existing vehicle sys tems ABS TC ECM coupled with added sensors to determine steering an gle and yaw A key input to the system is the pedal angle position sensor output The
11. ONIC THROTTLE CONTROL The Technological Need for ETC The clear goals of the automotive indus try are to improve fuel economy reduce emissions and improve function and safety for the driver To understand the design options available to accomplish these goals you need to know what pro duces the best results and what causes subpar performance These complicat ed goals are further complicated by trade offs that have to be made Fuel economy and emissions output per mile traveled are directly related to the size of the vehicle and the size of the engine In keeping with the laws of physics cutting fuel consumption is about either reducing the mass of the vehicle or reducing acceleration Since the systems are not perfect there s an other path that can be traveled by im proving efficiency to reduce losses The first thing to know is that most automobile engines are much larger than they need to be for most real world operating conditions The big V8 often selected for full size pickups is really chosen to pull a boat or trailer the owner may have in mind Yet trailer towing may amount to less than 1096 of the ac tual vehicle miles 9096 of the time a smaller engine would do just fine The fact that engines generally spend most of the time running at a small frac tion of their peak power output is re ferred to as the partial power problem Toyota says the Otto cycle engine is most efficient at 4096 to 4596 of its redlin
12. a and Magnum 2005 Ford Escape and Expedition 2005 GMC Envoy ESV and XL 2005 Jeep Grand Cherokee 2005 Lincoln Town Car 2005 Pontiac G6 Grand Prix and GTO 2005 Mazda MPV and Tribute 2005 Saab 9 7X 2005 Cadillac STS 2005 Chevrolet SSR 2005 Chrysler 300C 2005 Ford E 150 2005 Ford Freestyle 2005 Isuzu Ascender 2005 Lexus LS400 and GX470 2005 Mercury Mariner 2005 Land Rover LR3 2005 Mercedes Benz SLK350 2005 Toyota Avalon 2005 Buick LaCrosse Rendezvous and Rainier 2005 Chevrolet Cobalt Corvette and Malibu 2005 Mercury Grand Marquis Montigo and Sable 2005 Ford Crown Victoria Five Hundred Focus and Mustang 2005 Toyota 4Runner Sequoia Tacoma and Tundra 2005 Volvo S60 S80 V50 V70 XC90 BOSCH OBD II Network Diagnostics Strategy Based Diagnostics NOTES General Motors developed strategy based diagnostics for their technicians and the diagnostic procedure can be used on all vehicle applications e Verify the customer concern A technician needs to know how the system is Supposed to function normally before deciding that the system is malfunctioning A thorough customer interview or a diagnostic worksheet filled out by the customer is necessary before troubleshooting can begin e Preliminary checks Operate the suspect system and evaluate its performance Perform a thorough visual inspection of all components including fuses connectors grounds and harness routing This is also an ideal time to pul
13. and power of the drive train for hybrid vehicles can come from the internal combustion engine the generator and or the electric motor Combining and distributing the torque is handled by a planetary gearset that both Toyota and F ord call a power split device PSD In the PSD the carrier gear is connected to the engine the sun gear is connected to the generator and the ring gear is connected to the electric motor The planetary gear configuration provides decoupling of engine speed from vehicle speed While a hybrid drivetrain offers the possibility of improved fuel economy there are some added constraints F ord says one issue is that power split vehicles are sensitive to such noise factors as en gine torque mismatches that convention al vehicles are not These systems are also sensitive to overuse of the battery that may affect its durability To over come these issues Ford E scape M er cury M ariner engineers had to deter mine powertrain operating points com patible with the battery and high voltage bus architecture to ensure that power voltage and durability issues were met F ord says that the determination of a desired powertrain operating point for a conventional vehicle is relatively straightforward since there s only one path to the wheels from the power gen erating device the engine There are three variables that need to be deter mined the transmission gear the torque converter clutch state and the de
14. anol has a lower BTU rating for the same volume as gaso line more fuel is required to provide the same power at wide open throttle Illustrations courtesy University of Toyota Toyota is using what it calls Power Train Management on the Lexus LS 460 With this system the most suitable vehicle drive power is accurately ac complished with optimized engine torque and gear ratio Toyota s emphasis is on what the driver experiences which is torque at the drive wheels Lifts That Last A Lifetime Every Mohawk Lift features all pasifian mechanical stops and Mfinile positien hydraulie lacks All wa post liffs feature our patented hydraulic i adii system Two post lifts with ternum hydraulic equalizabon system Eight modets trom 7 000 30 000 Ib capacity 5nown Syptem i Toyota says that with conventional powertrain controls a target throttle opening and gear ratio are determined according to the driver s pedal angle in put Consideration in terms of throttle angle is given to other vehicle systems such as cruise control and vehicle stabil ity control VSC The result is that the 4 Full Vehicle Door Opening Fits Ni Asymme tric two post lift allows clear vem and d ear overhead s Circle 28 Open Front amp Total Under Vehicle Access k Ramp style four past lifts with ten models from 10 000 1 10 000 ID capacily shown FP Senes Lit gam 30 Acer Mk Ar Circle 29 a ek T 4 Space Saver Takes No Mor
15. ash reprogramming new control modules is necessary because new control modules need to know how that particular vehicle is configured in order to perform their function on the network properly e The first character identifies the system related to the trouble code P Powertrain B Body C Chassis U Network for years U was undefined Page 17 OBD II Network Diagnostics NOTES Page 18 BOSCH Example of Generic U Codes U0100 Lost Communication With ECM PCM A U0101 Lost Communication With TCM U0102 Lost Communication With Transfer Case Control Module U0103 Lost Communication With Gear Shift Module U0104 Lost Communication With Cruise Control Module U0105 Lost Communication With Fuel Injector Control Module U0106 Lost Communication With Glow Plug Control Module U0107 Lost Communication With Throttle Actuator Control Module U0108 Lost Communication With Alternative Fuel Control Module U0109 Lost Communication With Fuel Pump Control Module U0110 Lost Communication With Drive Motor Control Module U0111 Lost Communication With Battery Energy Control Module A U0112 Lost Communication With Battery Energy Control Module B U0113 Lost Communication With Emissions Critical Control Information U0114 Lost Communication With Four Wheel Drive Clutch Control Module U0115 Lost Communication With ECM PCM B U0116 Reserved by Document UO117 Reserved by Document U0118 Reserved by Do
16. cument U0119 Reserved by Document U0120 Reserved by Document U0121 Lost Communication With Anti Lock Brake System ABS Control Module Example of GM Manufactured Specific U Codes U1000 Class 2 Communication Malfunction U1001 U1254 Loss of XXX Communications U1002 U1015 Loss of serial communications for Class 2 devices U1016 Loss of Class 2 Communication with VCM U1016 Loss of Communications with PCM U1017 U1025 Loss of serial communications for Class 2 devices U1026 Loss of ATC Class 2 Communication U1027 U1039 Loss of Serial Communications for Class 2 Devices U1040 Loss of Class 2 Communications with ABS U1041 Loss of EBCM Communication U1042 Lost Communications with Brake Traction Control System U1043 U1055 Loss of Serial Communications for Class 2 Devices U1056 Loss of Communications with RSS U1057 U1060 Loss of Serial Communications for Class 2 Devices U1161 Loss of PDM Serial Data Bosch Diagnostics conducts courses on this subject as well as many other topics in the field of automotive and diesel technology For more information on courses in your area go to www boschtechinfo com or call 800 321 4889 BOSCH Invented for life
17. dentified in circuit wiring diagrams Do not attempt to conduct wiring diagnostic fault procedures such as voltage or resistance tests without proper service information The figure on the next page shows an example of a CAN system with terminating resistors BOSCH OBD II Network Diagnostics NOTES Traction Control 3 HEROS MEN E 120 0 i 10 Lateral Acceleration Sensor Signal protocols There are five basic signal protocols currently in use with the OBD II interface SAE J1850 PWM SAE J1850 VPM ISO 9141 2 ISO 14230 KW ISO 15765 CAN C amp B Li LL ISO 15765 4 CAN Hi Bus m ISO 15765 4 CAN Low Bus Page 5 OBD II Network Diagnostics BOSCH NOTES J1850 from the Society of Automotive Engineers Protocols Ford Standard Corporate Protocol Protocol operates at 41 6 KB sec with two wires on the bus SAE J1850 PWM 41 6 kbaud standard of the Ford Motor Company Pin 2 Bus Pin 10 Bus High voltage is 5 V Brn ESEUGMCUZEZLIEZLLILILLILZL EU Ls S E S E 01 09 2007 01 11 37 PM Example Waveform nA Recall Run i MA TET HET Save 5 Cursor Time Div 200 Secs CH 1 2 00 V DC CH 3 OFF CH 2 2 00 V DC CH 4 OFF f Level 2 00 V Nrml Source CH 1 Rising Edge MTS 5200 Engine Analyzer Vetronix Bosch Group 09 Jan 2007 13 21 57 SAE J1850 PWM MTS 5100 Robert Bosch LLC Page 6 BOSCH General Motors Class 2 Bus Pr
18. e rpm This is the point at which torque is at about 7096 to 8096 of its peak value for a given engine In this most efficient 42 MOTOR July 2007 This is the roller lifter used in Chrysler s cylinder shutdown operating range the engine produces about 40 of its peak power rating Let s use Toyota s 108 hp ECHO en gine as an example Given the numbers just mentioned it would be best if most of the time the engine output were in the range of 40 to 50 hp Unfortunately this is not enough for adequate acceler ation or hill climbing Calculations show that if the ECHO had only a 30 hp en gine it would need 30 seconds to accel erate to 60 mph If such a vehicle were to encounter a 10 grade it would slow down to 30 mph before it reached the top of the hill On the other hand only 15 hp or so is needed to maintain 60 mph on level roads and even less power is needed for idling and low speed travel The net result is that the engine power output that was chosen for adequate passing and hill climbing is larger than neces sary for most of the operating circum stances of the vehicle n addition engines are seldom oper ated under the circumstances that would produce the best results for fuel economy and emissions output For a typical engine with a redline of 5000 rpm the sweet spot should be at about 2000 rpm In practical terms most en gines actually operate in a much broad er range between idle and 3200 rpm There ar
19. e Space Than Scissors lift with flush or surface mount and ful under vehicle access Shrii Li z For details call 800 833 2006 10 yz Mole awk bw ial F ax 5 50 MOTOR July 2007 3 MOHAWK Park Amsterdam NY 12010 42 1289 WWW w mohawklifts com target throttle opening and target gear ratio are set separately n previous sys tems this situation worked well because each of the vehicle systems was not large and the desired accuracy require ments were not particularly high This situation has changed N ewer ve hicle systems with precrash safety sys tems and intelligent parking assistance IPA systems have caused the relation ships among vehicle systems to become more complicated t has become more difficult to align all the different systems to achieve the desired drive power Toyota says it has developed some thing called Vehicle D ynamics ntegrat ed M anagement VDIM to integrate the vehicle stability control traction control ABS and electric power steer ing ETC is used for VDIM sensor in puts and control actuators The VDIM system controls the drive power by se lecting the combination of engine pow er and transmission gear to give the needed drive wheel torque at the high est possible efficiency By having an in tegrated system the best choices for ig nition timing engine rpm and gearing can be chosen to deliver torque and ac celeration the driver senses The torque
20. e the occasional zooms to red line but they represent a small part of the true operational circumstances Given normal gearing the peak effi ciency point for a vehicle turns out to be around 55 mph The double nickel speed limit was not chosen randomly but rather with an eye to best fuel econ system Oil flow regulated by a computer controlled sole fF noid unlocks the lifter to prevent the valve from opening omy for the average vehicle F or a given distance traveled fuel economy tapers off at both higher and lower speeds H olding a constant speed is an advan tage as it avoids both the extra fuel needed for acceleration and the in creased emissions that often result from deceleration N ot surprisingly the sweet spot of engine efficiency is also the sweet spot of emissions output It s the cold start events and sudden speed changes that challenge emissions control systems E lectronic throttle control can actually help emissions through strategies that lean out the mixture in concert with re tarded ignition timing to assure an earli er light off for the converter Efficiency losses occur on both sides of the sweet spot for a given engine At high engine speeds friction among the piston the rings and the cylinders ac counts for more of an engines lost out put These friction losses become more significant as engine size is reduced Parasitic losses to engine accessories such as the oil and water pumps also in cr
21. ease as a function of rpm Another is sue is the need to richen the fuel mix ture to get maximum torque output from the engine It may help accelera tion but it doesn t help emissions output or fuel consumption The major cause of efficiency losses at low speed is called pumping loss Re ducing the output of an engine is ac complished by limiting the airflow into the engine The throttle plate restricts the intake of air by forcing the engine to drag air through a narrow or restricted inlet The restriction of the air intake Photos courtesy Chrysler HEM MOS Multi Disphacament Syshem Tirrus MOS Mode up i d cy Verde Speed Waveform courtesy Chrysler The black trace at the bottom of this screen capture shows The stepper motors on these throttle bodies are mounted how the MDS switches between four cylinder and eight on the side With direct computer control the throttle angle cylinder operation At higher speeds the load is lower and can be changed to adapt the engine throttle setting in the portion of the time in four cylinder mode increases creates a differential pressure across the throttle plate we know as intake mani fold vacuum Since the air entering the cylinder is below atmospheric pressure less air enters the cylinder The engine control system measures the pressure differential and reduces fuel input ac cordingly The reduced quantities of air and fuel result in the desired reduction
22. ent on D emand system reduces effec tive engine size during steady state low power conditions A key aspect of this system isthe ETC systems ability to cre ate a greater throttle angle without the need for the driver to change pedal an 46 MOTOR July 2007 What was once a simple pedal and spring arrangement has become a highly sophisticated sensor actua tor Triple redundant systems as sure that the driver s intent gets to the computer without error gle This is a key element to assuring that the only indication to the driver that four of the V8 55 cylinders are deactivated isthe light on the dash E missions Control ETC isa part of the strategy to reduce engine emissions during cold start up One way to cause quick heating in the catalytic converter is to retard timing and lean out the mix ture The ability to do this is limited by the loss of torque and power that results from these engine settings F or a given pedal position the driver will feel re duced power when the strategy is im plemented Software compensations to the throttle angle can be made that maintain the original pedal to throttle relationship the driver is used to ETC also can be used to control actu al throttle angle during acceleration and deceleration to minimize pumping loss es Often the throttle angle implemented by the ETC system could be more favor able than the driver is able to select The greatest impact on emissions performance of
23. f the V8 engine F our electric solenoids are controlled by the result of the E 38 s processing of the load algorithm These solenoids de termine the number of active cylinders by controlling oil flow to the lifters of the affected cylinders In an AFM equipped engine pump ing losses are reduced during deactiva tion primarily by the increase in intake manifold pressure D uring deactivation the remaining cylinders need reduced throttling in order to provide an equive lent amount of work Without electron ic throttle control the driver would no tice the deactivation as a sag in perfor mance Without the driver needing to change the pedal angle the software changes the throttle angle to reflect the fewer number of functioning cylinders AFM operation is load based The load is measured and combined in an al gorithm with the drivers demand for power as measured by throttle applica tion Active fuel management does not affect emissions output from the active cylinders F or the inactive cylinders no fuel is wasted or burned and the result is lower emissions for the distance traveled The key point here is that the only mechanical components needed are the three or four special valve lifters and the solenoids to control them for the cylin ders that are to be deactivated T he soft ware based control system uses inputs that guarantees the accuracy of the output Some pedal assemblies can feed back to the driver tact
24. gen Passat where the modules talk to each other on a CAN protocol network The CAN protocol is then transmitted to the IP instrument cluster module where the signal protocol is converted to ISO format for communication with the scan tool Freeze Control Example Waveform eo Recall Run E i Save Cursor Time Div CH 1 5 00V DC CH 3 OFF CH 2 5 00 Y DC CH 4 OFF Level 5 00 V Nrml E Source CH 1 Falling Edge MTS 5200 Engine Analyzer Vetronix Bosch Group 01 Mar 2007 12 55 45 ISO 9141 2 ISO 14230 In use by 1997 ISO 14230 was an upgrade to ISO 9141 2 One of the major enhancements of ISO 14230 was a faster wake up call ISO 14230 KWP2000 Keyword Protocol 2000 Pin 7 K line Pin 15 L line optional Physical layer identical to ISO 9141 2 Data rate 1 2 to 10 4 kbaud BOSCH OBD II Network Diagnostics CAN Systems NOTES Controller Area Network or CAN is the latest communication system within the automotive world CAN is a means of linking all of the electronic systems within a car together to allow them to communicate with each other As on board computers increase so does the number of different electronic systems Today s modern vehicles may have as many as 50 or more on board computer systems on them The information recorded and processed by each control module is often used by one or more control modules on the system A reguirement for a standardized means of guickly passing informati
25. ile in formation about the correctness of the desired throttle angle about engine load vehicle speed driver intention safety and emissions inputs in making the decision to shut down indi vidual cylinders The ETC system al ready in place is used to make sure the vehicle operates normally during the deactivation The Gen IV Vortec 5 3L takes ETC to the next level by taking advantage of the processing capability available in the E 38 computer The increased integra tion allows the elimination of the throt tle actuator control TAC module In previous systems the TAC module took commands from the E CM and operated the electric stepper motor that controls throttle position n the new system the ECM operates the throttle directly This direct link between the throttle and the computer speeds up response time Eliminating the TAC also reduces wiring reliability issues and the need to monitor the TAC module for correct op eration The flex fuel 5 3 requires no special fuel sensor E arlier flex fuel engines used a light reactive sensor to determine what blend of fuel was in the system The Gen IV engine uses a virtual sensor pro grammed into its software Based on readings from the oxygen sensors fuel level sensor and vehicle speed sensors the ECM determines the fuel blend and adjusts the fuel injector pulse width and the throttle angle as required The ETC system makes the needed throttle angle changes Because eth
26. is used in multimedia networks Multimedia systems require large volumes of data to be transferred in short amounts of time To transmit a digital TV signal with stereo sound requires a data transfer rate of around E 6 Mbit s MOST Media Oriented Systems a A Transport can transfer data at a rate of 21 2 Mbit s F e rj Star Interconnection of multiple ECU s in a star FT structure network control by central master ECU FT This system uses a master slave time triggered protocol The network is designed as a low cost local sub system single wire interconnect network for use in on off devices such as car seats door locks sunroofs rain sensors and door mirrors Terminating Resistors Terminating resistors are used in CAN systems to create proper electrical load between the CAN H and CAN L circuits This load helps to reduce electrical noise on the data circuits which allows for a cleaner voltage signal on the data bus Terminating resistors in the high speed CAN systems are required to be 120 ohms with a maximum range of 118 132 ohms Lower speed CAN systems may use different values CAN systems can use split termination which means there may be more than two terminating resistors in the system Terminating resistors may be physically located inside any of the control modules connected to the CAN harness with a junction connector The resistors may also be part of the wiring harness Terminating resistors may or may not be i
27. l up the service history on the vehicle e Perform published diagnostic system checks If there is a published diagnostic procedure that will help you narrow down the cause of the problem use it first Note This is the time to connect the scan tool and request diagnostic information from the control modules on the network e Check for bulletins If you have access to published service bulletins for the vehicle search those for a possible fix This can save time in the long run You can also print safety bulletins for your customers at this point as an added value e Stored diagnostic trouble codes DTC s and symptoms with no DTC s If there is a hard trouble code then follow the diagnostic procedure for the particular DTC If you have a repeatable symptom then use the Symptom Charts Both these procedures will quickly help you narrow your diagnostic focus e No published diagnostics When there is no DTC stored and no matching symptom for the condition in the service manual you will have to develop your own diagnostic process based on your understanding of how the circuit operates This is the time when there is no substitute for advanced systems training The graphic on the next page shows the diagnostic flow chart for Strategy Based Diagnostics Page 13 OBD II Network Diagnostics NOTES Page 14 BOSCH 11 Verify the customer concern 23 Perform preliminary checks Perform operational system check s
28. nnecting the Scan Tool Is there power on Pin 16 to power up the Scan Tool Many OEM scan tools may not have internal batteries and will require Pin 16 to have power in order for the scan tool to communicate Be aware that no power on Pin 16 may affect some aftermarket scan tools consult your operator s guide Many times Pin 16 will not have power due to something as simple as a blown cigarette lighter fuse Remember Pin 16 is Battery Power Un switched Many technicians panic when their scan tool doesn t power up off the 16 Pin connector In some cases the technician will think the computer or computer s are dead and not communicating with the scan tool A quick work around is to power up the scan tool through an alternate battery source or AC power source Remember Pin 16 has nothing to do with communication it is only there to power up your scan tool for diagnosis Pins 4 amp 5 are also important as one of these grounds will be needed for your Scan Tool to power up the OBD II link and establish a reference link for scan tool communication If you are having communication problems it is imperative that you check the integrity of these grounds In some instances one of these grounds may be open or have high resistance There is also a possibility that the scan tool might complete a ground that is faulty when the scan tool is not connected If the OBD connector has power or ground problems you should validate the connections when the scan tool is
29. oard control units Today s modern vehicle will have on board control modules controlling vehicle components such as the engine antilock braking system transmission instrument panel chassis and body control functions to name just a few An on board control module does more than just make sure its own input and output devices work correctly The on board controller also participates and communicates in one or more communication networks in the vehicle These vehicle networks exist to allow the sharing of information among components and to reduce the numbers of wires and sensors required in the vehicle The second area in which microcontrollers are changing the automotive industry concerns the way we interact with our vehicles Computers are now common in the passenger area and consumers can now interact with their vehicles in a variety of ways This allows consumers to run already familiar programs in the vehicle email GPS navigation calendar management etc Lexus Navigation Center Page 1 OBD II Network Diagnostics NOTES Page 2 3 BOSCH The second phase of this migration also allows the automotive technician to interact with the vehicle s on board controllers gathering information controlling the vehicle directly and aiding in the diagnosis of problems This interaction can occur with the use of a scan tool or in some case accessing the on board controller directly through an operation sequence or a control
30. ommunication CAN networks can communicate internally but not with the scan tool Many CAN modules will talk with each other and a gateway or translator module will convert the protocol so a scan tool can understand it CAN Translators VW Example Instrument clusters from 08 99 gt are integrated into the vehicle CAN Data Bus network The CAN Bus on board diagnostic Interface J533 which is integrated into the instrument cluster enables data to be exchanged between the vehicles CAN Data Bus network and the Data Link Connector DLC K wire The CAN Bus On Board Diagnostic Interface J533 has specific on board diagnostic OBD capabilities that are accessed by using scan tool address word 19 Gateway The next page shows a network diagram of a VW Passat with three different networks Page 10 B O S CH OBD II Network Diagnostics NOTES Engine Control DSG Connector Module J220 DLC T16 Scan Tool CAN Airbaa CM J234 Steering Angle Sensor G85 Data Bus On Board Steering Diagnostic Interface J533 Vihas CM E221 G Ignition Starter Switch D ir Instrument Cluster CM J285 I Anti Theft Engine Disable Steering Column Immobilizer IV CM J334 Electronic Systems Wiper Motor CM J400 Rain Light Recognition Convenience CAN Sensor G397 Drivetrain CAN bus Alarm Horn H8 Convenience CAN bus Infotainment AN bus LIN Bus Instrument Cluster N bus CAN bus Wire Communications
31. on between the control modules was needed leading to the development of CAN CAN History CAN protocol was created in 1984 by Robert Bosch Corporation with anticipation of future advances in on board electronics The first production application was in 1992 on several Mercedes Benz models CAN is now being used on more and more new vehicles By 2008 all new vehicles sold in the U S will be required to have a CAN compliant diagnostic system CAN Protocols ISO 15765 CAN B amp C CAN B the medium speed network nominally about 125 kB sec will be used for body electrical systems and normally will operate at 83 3 kB sec On some Mercedes cars there may be as many as 30 modules on the CAN B bus Pin 3 CAN High Pin 11 CAN Low CAN C is a 500 kbit s high speed two wire system for powertrain transmission and ABS modules CAN C is intended to operate at a 500 kB sec baud rate about 50 times faster than GM s Class 2 data bus version of J1850 and over 60 times faster than ISO 9141 2 Pin 6 CAN High Pin 14 CAN Low Note that Pins 4 chassis ground 5 signal ground and 16 battery positive are present in all configurations The next page shows a CAN High and CAN Low waveform Page 9 OBD II Network Diagnostics BO S C Hi NOTES Trigger source Mode Ch2 cut Auto Time Diagnosis RN EFI T LTE EAN STI OE re Screen Capture using KTS 570 lab scope Robert BoschLLC Internal CAN C
32. otocol operates at 10 4 kB sec with one communication wire Chrysler also has an adaptation of the GM Class 2 protocol Pin 2 Bus Bus idles low _ High voltage is 7 V _ Decision point is 3 5 V Message length is restricted to 11 bytes including CRC Component Selection Trig Setup Lead Glitch Help On Defalt Signal Setup Finder 1 p Time Div Level 3 25 V Nrml I Source CH 1 Rising Edge DR ban MNA 12 21 34 lt ATC ZD Cnain fimokrenr 0 amp 5 SAE J1850 VPM 47 m nan mar mbi ms ISO 9141 2 from the European influenced International Standards Organization This is a single wire where the ISO modules talk only when asked and only to the scan tool not to each other This protocol is slower than GM and Chrysler versions of SAE J1850 The ISO 9141 2 protocol has a long wake up call which allows for each control module to report PID data ISO 9141 2 protocol has a data rate of 10 4 kbaud and is primarily used in Chrysler European and Asian vehicles OBD II Network Diagnostics NOTES Page 7 OBD II Network Diagnostics NOTES Page 8 BOSCH Pin 7 K line Pin 15 L line optional UART signaling though not RS 232 voltage levels K line idles high High voltage is Vbatt Just because a vehicle has an ISO protocol does not mean that the control modules are unable to talk to each other An example would be a 2001 Volkswa
33. panel on the vehicle 2005 Dodge Neon with Idle Air Control Motor DTC P0508 This code was obtained by H E cycling the ignition key on off three times Notice how the code is displayed directly on the dash panel KTS 200 Communicating with Generic OBD ll interface Robert Bosch LLC Network and Scan Tool Communication An automotive controlled network consists of multiple series of control modules electronically communicating complex information and requests in a digital language format This digital language is known to technicians as vehicle protocols Modules can be connected on the network in serial or parallel interface The term used for this type of communication interface is called Multiplexing and can be carried through single or dual circuits When a scan tool is connected and interfaced into the network it should be considered as one other control module on the network B BOSCH OBD II Network Diagnostics Primary Purposes of Networking NOTES One of the major driveability concerns in automotive diagnostics is circuit related problems due to bad connections creating opens shorts resistance and voltage drop problems Networks help resolve these problems by eliminating miles of wires connections and splices With networking a fuel pump circuit that would normally be wired to the PCM to be commanded on could now be wired to a Rear Control Module REM reducing wire length and potential circuit problems With ne
34. removed OBD II Network Diagnostics NOTES Page 15 OBD II Network Diagnostics NO TES ontro sis 1 channel multimeter measurement Exit multimeter with lt lt 50 O 000 um 50 12 11V afa po a a aa fs gt start A WR Bosch appicationsm fimBosce Controlun Hfuttedbno rat SOLEO RORIS 127 Checking Power to Chassis Ground KTS 570 Robert Bosch LLC Using the scan tool in conjunction with a 16 Pin Breakout Box Different types of 16 Pin breakout boxes are available in the aftermarket Some breakout boxes hook up in parallel allowing you only the ability to probe the circuit with a scope or DVOM Other breakout boxes like the AES Line Spi hook in a series circuit allowing the scan tool to command data bus protocols from the on board computer while diagnosing with a lab scope or DVOM mastertech E n A PED ITY rs e le je DED az e AES LineSpi MTS 5200 MTS 3100 connected to Ford ISO 9141 2 in Module Status Check www aeswave com Page 16 B BOSCH OBD II Network Diagnostics What Computers Are Talking on the Network NOTES When diagnosing vehicle driveability problems with networked computer modules know what computers are on the network for the particular vehicle application you are working on Many vehicle applications may add or delete computer modules based on the amount of accessories and options Most electronic information sys
35. sired engine torque The drivers in tent is reported by the pedal angle sen sor The gear and torque are determined by computer algorithm with the result that the throttle angle is controlled In a hybrid vehicle there are three power producing devices the genera tor the motor and the engine The con trol system determines what the driver demanded wheel torque is by way of the pedal angle sensor F rom this the computer software can choose the opti mum combination of desired engine speed and desired wheel torque E n gine speed is the result of the throttle position algorithm s control of the throt tle angle Wheel torque is the result of the choice of power sources and the gearing between them and the wheels In the power split hybrid electric vehi cle generator torque and generator speed and therefore generator pow er are largely determined by the desired engine speed and actual engine torque So the battery power limit is essentially a constraint on motor power Since motor speed is determined by vehicle speed this effectively limits motor torque M o tor torque is also limited by what the driver wants in terms of driveability The hybrid control system has to manage the interactions of the three possible power sources Electronic throttle control inte grated into the system is used to accept the input of the driver and to then con trol the engine s output in accordance with the other two sources of power
36. tems will have a computer network schematic at the beginning of the wiring diagrams section 14 1 Module Communications Network System overview Hot at ai Central Junc Electronic park Rear Electronic ABS control Powartrain Con tion Box CJB brake module Module REM module 20213 trol Module o 144068 138520 PCM 124650 Front Electronic Driver seat Module FEM module 138525 140718 ABS test con Restraints con Auxillary Junc trol module tion Box AJB 148321 interior Aud o unit instrument cius Electronic Auto ABS control 18808 ter matic Tampera module 2C213 ture Control EATC module 19580 Powertrain Con Joint connector trol Module 4 PCM 124650 Data Link Con nactor DLC 14489 Courtesy Ford Motor Company 2 2 Ford Motor Company Network Schematic Ford Technical Publications http www fordinstallersupport com The Invention of the U Code U codes were classified by the SAE as the 4 item for trouble code descriptions In the early years of OBD II the U designation was classified as undefined U codes are becoming more prevalent on today s modern vehicles adding more advanced on board diagnostics Control modules are now programmed to know what other modules they should be in communication with on the network Based on network communication problems a U code could be set if a particular module was not communicating on the network Fl
37. they require moder ate to significant changes to the engine s architecture to successfully package the VVT components Cam phasers not only take up space but also add to the vehicle in terms of complexity weight and cost Using ETC to Achieve System Goals Automakers have taken this research into engine efficiency and done their best to make sure the engine spends more of its time in and around the sweet spot They know that the vehicle has to feel normal to the driver and have gone to great lengths to make that happen From the driver s standpoint what the computing platforms are ad justing and controlling is strictly in the background Getting greater effi ciency is accomplished in several ways Transmission Control Keeping the engine at its rpm sweet spot is accom plished by having more of the need for rpm compensation between the engine and the drive wheels handled by the transmission Six seven and eight speed transmissions as well as CVTs Photo courtesy Mikuni Corp are becoming commonplace As CVTs are still limited in their peak torque handling capability vehicles with high output engines have stayed with con ventional multispeed transmissions Ford and GM are in production now on their joint venture six speed trans mission About 8596 of the components are meant to be shared by both manu facturers E xpectations are for a 496 in crease in fuel economy while at the same time providing a 796 improve
38. tworking the command from the PCM to turn on the fuel pump could be sent to the REM module over the network that would then activate the fuel pump circuit Note As networks evolve look for control modules to be located in various quadrants within the vehicle and components located near that quadrant reporting to a specific control module Electrical terminal diagram 2 Engine control unit ABS control unit Automatic transmission control unit Airbag control unit A C control unit Central electronics control unit 1 Central electronics control unit 2 Central electronics control unit 3 Instrument cluster Steering column module Diagnosis socket OBD 8102505 rr 20 10 9 19 A M A A VG 2 9 8 r m hn 13 14 12 14 16 A6 45 A5 12 A741 A6 23 Se 84 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 2004 Volvo S 80 Control Module Network Configuration Circuit Diagram from CAS SIS Diagnostics ESlI tronic Robert Bosch LLC Page 3 OBD II Network Diagnostics NOTES Page 4 BOSCH Network Topology Linear Interconnection of multiple ECU s on common linear bus A multi master principle is generally used allowing high stability with enhanced fault localization This system is used in drivetrain and body network systems Ring Short path interconnection of multiple ECU s in a fiber optic series ring The information passes through each ECU This system
39. with ETC as a key input The 3 9L V6 also uses AF M but in combination with VVT GM says the 3 9 is the first to use both cylinder deac tivation and VVT on the same engine U nder light load conditions either en gine can deactivate half the cylinders Real world fuel savings of 7 is what GM is advertising although the benefit reportedly is greater for those who do a lot of steady state highway cruising The E38 ECM measures load con ditions based on inputs from vehicle sensors such as ETC and interprets that information to manage more than a hundred engine operations F uel injec tion spark control and electronic throt tle control are all included When loads are light the engine computer automat ically closes both the intake and exhaust valves while at the same time cutting fuel delivery When the driver demands acceleration or increased torque to move aload the cylinders are reactivated In these systems ETC is used to bal ance torque to prevent the driver from feeling the cylinders as they come or go off stream D uring deactivation both valves are closed The energy used to compress the air in the cylinder is re turned to crankshaft on the downstroke as the trapped air acts as a spring The 48 MOTOR July 2007 transition takes less than 20mS and the driver never notices it The actual hardware used to control the deactivation is called a lifter oil manifold assembly LOM A and is lo cated in the valley o
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