HOW TO PROCEED WITH TROUBLESHOOTING
Contents
1. 2005 LEXUS IS300 RM1140U Author Date 24 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED IN 25 SYSTEMS In diagnostic trouble code check it is very important to determine whether the problem indicated by the diag nostic trouble code is still occurring or occurred in the past but returned to normal at present In addition it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic trouble code is directly related to the problem symptom or not For this reason the diagnostic trouble codes should be checked before and after the symptom confirmation to determine the current conditions as shown in the table below If this is not done it may depending on the case result in unnecessary troubleshooting for normally operating systems thus making it more difficult to locate the problem or in repairs not pertinent to the problem Therefore always follow the procedure in correct order and perform the diagnostic trouble code check DIAGNOSTIC TROUBLE CODE CHECK PROCEDURE Diagnostic Trouble Code Check Make a note of and then clear Diagnostic Trouble Problem symptoms Same diagnostic Problem is still occurring in the diagnostic Code Display exist trouble code is circuit displayed Confirmation Diagnostic Trouble Problem Condition of Symptoms Code Check Normal code is The problem is still occurring in a place displayed other than in the diagnostic circuit The diagnostic2. 28 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED SYSTEMS pA HEAT METHOD When the problem seems to occur when the suspect area is heated Heat the component that is the likely cause of the malfunction with a hair dryer or similar device Check whether or not if the malfunction occurs NOTICE 1 Do not heat to more than 60 C 140 F Exceeding this temperature may damage components 2 Do not apply heat directly to parts in the ECU WATER SPRINKLING METHOD When the malfunction seems to occur on a rainy day or in a high humidity condition Sprinkle water onto the vehicle and check whether or not if the malfunction occurs NOTICE 1 Never sprinkle water directly into the engine compart ment Indirectly change the temperature and humidity by applying water spray onto the front of the radiator 2 Never apply water directly onto electronic components HINT If a vehicle is subject to water leakage the leaked water may damage the ECU When testing a vehicle with a water leakage Fi6649 problem special caution must be taken Turn on all electrical loads including the heater blower head lights rear window defogger etc and check to see if the mal function occurs Bo2390 2005 LEXUS IS300 RM1140U Author Date 28 IN 29 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED SYSTEMS 4 DIAGNOSTIC TROUBLE CODE CHART Use Diagnostic Trouble Codes DTCs from the DTC checks in the table below
3. A Ignition Switch ACC is located in the sensors actuators wire har lt Z ness or ECU INSPECTION PROCEDURE y 1 Check continuity between terminal KNK of ECM connector and body ground y LOCK PREPARATION LQ KNK a Remove the glove compartment See page SF 68 Se b Disconnect the E6 connector of ECM EDL ne i CHECK Gam j Measure resistance between terminal KNK of ECM connector GE and body ground E6 Connector OK ini vee Resistance 1 MQ or higher A00265 4 A00255 OK Go to step 3 cs 2 Check knock sensor See page SF 61 OK Replace knock sensor e Indicates the place to check the voltage or resistance e Indicates the connector position to checked from the front or back side Wire Harness Check from the connector back side Check from the connector front side without harness with harness In this case care must be taken not to bend the terminals e Indicates the coneiien pi img connector of ECU during the check E6 Connector E6 Connector Connector being checked is connected Connector being checked is disconnected V08425 2005 LEXUS IS300 RM1140U Author Date 32
4. DTC Detecting Condition Trouble Area Open or short in knock sensor1 circuit No knock sensor 1 signal to ECM with e gine speed P0325 Knock sensor 1 loo eness 1 200 rpm or more e ECM If the ECM detects the above diagnosis conditions it operates the fall safe function in which the corrective retard angle value is set to the maximum value e Indicates the diagnostic trouble code DTC DTC set parameter and suspect area of the problem WIRING DIAGRAM e Wiring Diagram This is a wiring diagram of the circuit Use this diagram together with an ELECTRICAL EGM WIRING DIAGRAM to thoroughly understand the Knock Sensor 1 circuit Wire colors are indicated by an alphabetical code B Black L Blue R Red BR Brown LG Light Green V Violet G Green O Orange W White GR Gray P Pink Y Yellow SB Sky Blue The first letter indicates the basic wire color and the second letter indicates the color of the stripe V08423 2005 LEXUS IS300 RM1140U Author Date 31 IN 32 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED SYSTEMS e Indicates the position of the ignition switch during the check e Inspection Procedure LOCK OH Use the inspection procedure to determine if S Ignition Switch LOCK OFF A Ignition Switch ON the circuit is normal or abnormal If it is abnor START ace mal use it to determine whether the problem GA Ignition Switch START
5. IN 22 INTRODUCTION HOW TO TROUBLESHOOT ECU CONTROLLED y STEMS HOW TO PROCEED WITH TROUBLESHOOTING Carry out troubleshooting in accordance with the procedure below Only a basic procedure is shown Details in the Diagnostics section show the most effective methods for each circuit Confirm troubleshooting proce dures first for the relevant circuit before beginning troubleshooting of that circuit IN04T 22 Vehicle Brought to Workshop 1 Customer Problem Ask the customer about the conditions and the Analysis environment in which the problem occurred 2 Symptom Confirmation 3 and Diagnostic Trouble CJ Symptom Simulation Code Check ne 2 3 Confirm the symptoms and the problem conditions and check the diagnostic trouble codes When the problem symptoms do not appear during confirmation use the symptom simulation method described later on W 4 Diagnostic Trouble Code Chart S Problem Symptoms Table 4 5 6 Check the results obtained in Step 2 Confirm the inspection procedure for the system or the part that should be checked using the diagnostic 6 Circuit Inspection or Parts trouble code chart or the problem symptoms table Inspection 7 Check and repair the affected system or part in p accordance with the instructions in Step 6 8 8 comnnnetion test After completing repairs confirm that the problem has been elimin
6. ODUCTION HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS 2 SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK The diagnostic system in the LEXUS IS300 fulfills various functions e The first function is the Diagnostic Trouble Code DTC Check In a DTC Check a previous malfunc tion s DTC can be checked by a technician during troubleshooting A DTC is a code stored in the ECU memory whenever a malfunction in the signal circuits to the ECU occurs e Another function is the Input Signal Check which checks if the signals from various switches are sent to the ECU correctly By using these check functions the problem areas can be narrowed down and troubleshooting is more effective Diagnostic functions are incorporated in the following systems in the LEXUS IS300 Diagnostic Trouble Input Signal Check System Code Check Sensor Check Engi a UB with Check Mode Aut tic Transmission k A E AR with Check Mode ABS with EBD amp BA amp TRAC System ABS with EBD amp BA amp TRAC amp VSC System e I as Diagnostic Test Mode Active Test 2 Cruise Control System Engine Immobiliser System Combination Meter System Body Control System o Multiplex Communication System fe oa o LEXUS Navigation System 4 Air Conditioning System 2
7. ated To be absolutely sure the problem no longer ex End ists perform the confirmation test under the same conditions and environment as when it occurred the first time 2005 LEXUS IS300 RM1140U Author Date 22 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED IN 23 SYSTEMS 1 CUSTOMER PROBLEM ANALYSIS e The 5 items in the table below are important points in the problem analysis In troubleshooting the problem symptoms must be confirmed accurately Preconceptions should be discarded in order to give an accurate judgement To ascertain what the problem symptoms are it is extremely important to ask the customer about the problem and the conditions at the time it occurred Important Points in the Customer Problem Analysis What Vehicle model system name When Date time occurrence frequency e Where Road conditions e Under what conditions Running conditions driving conditions weather conditions e How did it happen Problem symptoms Sample Supplemental restraint system check sheet CUSTOMER PROBLEM ANALYSIS CHECK SUPPLEMENTAL RESTRAINT SYSTEM Check Sheet Inspectors re A Ee een Date Vehicle Brought In Date Problem First Occurred weater O Fine O Cloudy O Rainy O Snowy O Other O Starting O Idling Vehicle Operation O Driving O Constant speed O Acceleration O Deceleration O Other 2005 LEXUS IS300 RM1140U Author Date 23 IN 24 INTR
8. rcuit DI 147 No initial combustion Does not start 2 Fuel pump control circuit DI 151 3 Engine control module ECM IN 29 No complete combustion Does not start 1 Fuel pump control circuit DI 151 1 Starter signal circuit DI 144 Engine cranks normally Difficult to start 2 Fuel pump control circuit DI 151 3 Compression EM 3 er DI 144 Cold engine Difficult to start 1 Starter signal circuit DI 151 2 Fuel pump control circuit Hot engine 1 Starter signal circuit l DI 144 2 Fuel pump control circuit DI 151 ed Poor idling 1 A C signal circuit Compressor circuit 2 ECM power source circuit 1 A C signal circuit ing 2 Fuel pump control circuit 1 Compression 2005 LEXUS IS300 RM1140U Author Date 30 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED IN 31 SYSTEMS 6 CIRCUIT INSPECTION How to read and use each page is shown below e Diagnostic Trouble Code No and Detection Item e Circuit Description The major role and operation of the circuit and its component parts are explained y DTC P0325 Knock Sensor 1 Circujt Malfunction CIRCUIT DESCRIPTION M Knock sensor is fitted to the cylinder block to detect engine knocking This sensor contains a piezoelectric element which generates a voltage when it becomes deformed which occurs when the cylinder block vibrates due to knocking If engine knocking occurs ignition timing is retarded to suppress it DTC No
9. rmal code displayed e Normal code displayed e Problem symptoms exist e Problem symptoms exist e No problem symptoms exist i Troubleshooting of problem indicated by diagnostic trouble code problem symptom Troubleshooting of each L 2005 LEXUS IS300 RM1140U System Normal If a diagnostic trouble code was displayed in the initial diagnostic trouble code check it indicates that the trouble may have occurred in a wire harness or connector in that circuit in the past Therefore check the wire harness and con nectors see page IN 33 Author Date 26 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED IN 27 SYSTEMS 3 SYMPTOM SIMULATION The most difficult case in troubleshooting is when no problem symptoms occurring In such cases a thor ough customer problem analysis must be carried out Then simulate a simulation of the same or similar conditions and environment in which the problem occurred in the customer s vehicle should be carried out No matter how much skill or experience a technician has troubleshooting without confirming the problem symptoms will lead to something important in the repair operation being overlooked and lead to mistakes or delays in repairs For example With a problem that only occurs when the engine is cold or occurs as result of vibration caused by road dur ing driving the problem can never be determined as long as the s
10. rottle position sensor circuit Throttle position sensor e ECM Qsition Sensor Switch scformance Prob 2005 LEXUS IS300 RM1140U e Throttle position sensor Author Date 29 IN 30 INTRODUCTION HOWTO TROUBLESHOOT ECU CONTROLLED SYSTEMS 5 PROBLEM SYMPTOMS TABLE The suspected circuits or parts for each problem symptom are shown in the table below Use this table to troubleshoot when during a DTC check a Normal code is displayed in the diagnostic trouble code check but the problem is still occurring Numbers in the table show the inspection order in which the circuits or parts should be checked HINT In some cases a problem is not detected by the diagnostic system even though a problem symptom is pres ent It is possible that the problem is occurring outside the detection range of the diagnostic system or that the problem is occurring in a completely different system e Page Indicates the page where the flow chart for each circuit is located e Circuit Inspection Inspection Order Indicates the circuit which needs to be checked for a problem symptom e Circuit or Part Name e Problem Symptom Indicates the circuit or part which needs to be checked PROBLEM SYMPTOMS TABL Y N Symptom Suspect Area See page ST 2 Engine does not crank Does not start 1 Starter and starter relay ST 17 N 1 ECM power source ci
11. to determine the trouble area and proper inspection procedure The engine diagnostic trouble code chart is shown below as an exam ple e DTC No Indicates the diagnostic trouble code e Page or Instructions Indicates the page where the inspection procedure for each circuit is to be found or gives instructions for checking and repairs e Trouble Area Indicates the suspect area of the problem e Detection Item Indicates the system of the problem or contents of the problem DTC CHART SAE Controlled HINT e ECM DTG No Seg page Detection Item Trouble Area MIL Memory ne e Open or short in mass air flow meter circuit DI 24 Mass Air Flow Circuit Malfunction e Mass air flow meter O O Mass Air Flow Circuit Range Performance Problem P0101 DI 28 e Mass air flow meter Intake Air Temp Circuit Malfunction P0110 DI 29 Open or short in intake air temp sensor circuit e Intake air temp sensor e ECM a P0115 DI 33 Engine Coolant Temp Circuit Malfunction e Open or short in engine coolant temp sensor circuit e Engine coolant temp sensor e ECM O P0116 DI 37 Engine Coolant Temp Circuit Range Performance Problem e Engine coolant temp sensor e Cooling system OTOJ male edal Position Sensor Switch e Open or short in th
12. trouble code displayed first is either for a past problem or it is a secondary problem No problem The problem occurred in the diagnostic symptoms exist circuit in the past Normal Code Display Problem symptoms Normal code is The problem is still occurring in a place exist displayed other than in the diagnostic circuit No problem Normal code is The problem occurred in a place other symptoms exist displayed than in the diagnostic circuit in the past 2005 LEXUS IS300 RM1140U Author Date 25 IN 26 Taking into account the points on the previous page a flow chart showing how to proceed with troubleshoot ing using the diagnostic trouble code check is shown below This flow chart shows how to utilize the diagnos tic trouble code check effectively then by carefully checking the results indicates how to proceed either to INTRODUCTION et TO TROUBLESHOOT ECU CONTROLLED Y STEMS diagnostic trouble code troubleshooting or to troubleshooting of problem symptoms table Diagnostic trouble code check Making a note of and clearing of the diagnostic trouble codes displayed 4 Symptom confirmation Problem symptoms exist exist No problem symptoms Simulation test using the symptom simulation methods v 4 Diagnostic trouble code check J e Diagnostic trouble code displayed e No
13. ymptoms are being checked on stationary vehicle or a vehicle with a warmed up engine Vibration heat or water penetration moisture is difficult to reproduce The symptom simulation tests below are effected substitutes for the conditions and can be applied on a stationary vehicle Important Points in the Symptom Simulation Test In the symptom simulation test the problem symptoms as well as problem area or parts must be confirmed First narrow down the possible problem circuits according to the symptoms Then connect the tester and carry out the symptom simulation test judging whether the circuit being tested is defective or normal and also confirming the problem symptoms at the same time Refer to the problem symptoms table for each sys tem to narrow down the possible causes of the symptom fia VIBRATION METHOD When vibration seems to be the major cause CONNECTORS Slightly shake the connector vertically and horizontally WIRE HARNESS Slightly shake the wire harness vertically and horizontally The connector joint fulcrum of the vibration and body through portion are the major areas that should be checked thoroughly PARTS AND SENSOR Apply slight vibration with a finger to the part of the sensor considered to be the cause of the problem and check wheth er or not the malfunction occurs HINT Applying strong vibration to relays may result in open relays V07268 2005 LEXUS IS300 RM1140U Author Date 27 IN
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