Engine Controls - Self-Diagnostics: Diagnosis Lexus SC II

TESTING PROCEDURE

To ensure correct diagnosis and repair, testing should be done in following sequence

1. Record Customer Complaint Ensure all customer complaints or observations are recorded. Test drive vehicle with customer when necessary for malfunction verification.
2. Retrieve Diagnostic Trouble Codes Connect appropriate OBD-II scan tool. Retrieve codes and record any freeze-frame data. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-151781-S29975222372003010800000) .
3. Clear Trouble Codes Clear DTCs using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151781-S26653383402003010800000) .
4. Perform Visual Inspection Inspect all connectors of suspect circuit or component. Ensure all connections are clean and tight.
5. Confirm Symptoms & Trouble Codes Perform road test. Determine if original symptoms are still present. Retrieve codes.
6. Diagnose & Repair Diagnostic Trouble Codes Perform diagnosis and repair procedures as needed. See «DIAGNOSTIC TESTS»(ref-151781-S38241362492003010800000) . If no codes are present, proceed to «TROUBLE SHOOTING - NO CODES»(ref-151782) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
7. Verification Procedure After repairs have been completed, clear all DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151781-S26653383402003010800000) . Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

1. Turn ignition on with engine off. MIL should come on and remain on. If MIL does not come on, check bulb circuit on instrument cluster and wiring circuit between MIL and ECM. See «ENGINE PERFORMANCE»(ref-158977-S13145987782003110400000) in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
2. Start engine and ensure MIL goes off. If MIL remains on with engine running, a malfunction is detected. Proceed to «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-151781-S29975222372003010800000) .

RETRIEVING DIAGNOSTIC TROUBLE CODES

Diagnostic Trouble Codes (DTCs) may be retrieved using Lexus scan tool or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Lexus scan tool or OBD-II scan tool may be operated in NORMAL mode when retrieving trouble codes. If no codes are stored in NORMAL mode, Lexus scan tool may be used in CHECK mode to determine if any first trip DTCs are stored. OBD-II scan tools that comply with SAE standard J-1979 may be used in MODE 7 (CONTINUOUS TEST RESULTS function) to determine if any first trip DTCs are stored. NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). MODE 7 or CHECK mode is used to check for DTCs when operating vehicle to simulate conditions in which DTC was set. CHECK mode contains a higher sensing ability to detect malfunctions and helps locate problems caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when scan tool is switched from NORMAL mode to CHECK mode, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.

CHECK Mode Code Retrieval (Lexus Scan Tool Only)

1. Ensure vehicle battery is fully charged (at least 11 volts). Shift transmission/transaxle into Neutral (M/T) or Park (A/T). Turn A/C and all accessories off. Ensure throttle is in idle position.
2. Turn ignition off. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 DLC No. 3 connector is located under left side of instrument panel. Turn ignition on with engine off. Turn scan tool on.
3. Switch scan tool from NORMAL mode to CHECK mode. CHECK mode is operational if MIL on instrument cluster flashes. Start engine. Ensure MIL goes off. Try to simulate conditions of driveability complaint described by customer. NOTE: If ignition is turned from ON to ACC or OFF position, all DTCs and freeze-frame data will be erased. DO NOT switch modes or turn ignition off until all DTCs and freeze-frame data are recorded.
4. Record any DTCs and freeze-frame data displayed for system diagnosis. If driveability problem exists and no codes are present, go to «TROUBLE SHOOTING - NO CODES»(ref-151782) article for diagnosis by symptom.
5. If any DTCs are present, perform appropriate diagnostic test. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-151781-S21913940602003022400000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-151781-S33978050772003010800000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-151781-S40978373742003010800000) under DETECTION LOGIC under INTRODUCTION.
6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151781-S26653383402003010800000).

CLEARING DIAGNOSTIC TROUBLE CODES

1. After performing repairs, clear ECM memory of all stored Diagnostic Trouble Codes (DTCs) and freeze-frame data. DTCs and freeze-frame data may be cleared using scan tool and by following scan tool manufacturer's instructions. NOTE: If using Lexus scan tool, DTCs and freeze-frame data may be cleared by switching from CHECK mode to NORMAL mode or from NORMAL mode to CHECK mode.
2. DTCs and freeze-frame data may also be cleared by removing EFI fuse and ECTS fuses (if equipped with electronic throttle control system) from fuse/relay box located in engine compartment. DTCs and freeze-frame data may also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, alarm, seats, etc.) will be cancelled and must be reset.

TROUBLE CODE TEST DRIVE CONFIRMATION

1. On certain Diagnostic Trouble Codes (DTCs), once DTC has been cleared from ECM memory, a DTC test drive confirmation test can be performed to verify repairs made and that DTC does not reset. Test drive confirmation test will duplicate conditions required to set specified DTCs.
2. Test drive confirmation test lists procedure to be performed to check that DTC does not reset. Test drive confirmation tests apply only to specific DTCs. Test drive confirmation test will be included with proper DTC diagnostic test in «DIAGNOSTIC TESTS»(ref-151781-S38241362492003010800000) .

DLC NO. 3 INSPECTION

1. If scan tool displays UNABLE TO CONNECT TO VEHICLE when scan tool is connected, try scan tool on another vehicle. If scan tool operates on another vehicle, go to next step. If scan tool does not operate on another vehicle, problem is probably with scan tool.
2. Check DLC No. 3 for loose or damaged terminals. Ensure DLC No. 3 terminals are in correct position in connector. See «ENGINE PERFORMANCE»(ref-158977-S13145987782003110400000) in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If connector and terminals are okay, go to next step.
3. Check voltage and resistance between ground and specified terminal on DLC No. 3. See «DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-151781-S39480457172003010800000) table. (Scheme 21) If voltage and resistance readings are not as specified, check wiring circuit. See «ENGINE PERFORMANCE»(ref-158977-S13145987782003110400000) in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 21

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TESTS

Note. For identification of circuits, terminals and wire colors referenced in following testing, see ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

Diagnosis & Repair

1. Start engine. If engine speed is normal when disconnecting OCV connector, then idle is rough or engine stalls when applying battery positive voltage between terminals of the OCV, go to next step. If engine speed is not to specification, go to step 3.
2. Disconnect the C2 or C3 OCV connector. Apply battery positive voltage between the terminals of the OCV. (Scheme 22) Check the engine speed. If idle is rough or engine is stalled, go to next step. If idle is not rough, replace camshaft timing oil control valve assembly.
3. Using oscilloscope during idle, check the waveform between terminals E2 (OCV+ and OCV-) and E4 (OCR+ and OCR-) of ECM connectors. The waveform frequency is lengthened as the engine speed becomes higher. (Scheme 23) If okay, go to next step. If not okay, check and replace ECM.
4. Disconnect C2 or C3 OCV connector. (Scheme 24) Disconnect E2 and E4 ECM connectors. (Scheme 25) Check the continuity between the wire harness side connectors. If okay, check for intermittent problems. If not okay, repair or replace harness and connector as necessary.

Scheme 22

Scheme 23

Scheme 24

Scheme 25

1. Check valve timing. Check for loose and jumping teeth of timing belt. Adjust valve timing as necessary. If okay, go to next step.
2. Check and replace ECM.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0101 is displayed, replace MAF sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest. If only DTC P0116 or P0125 are displayed, check thermostat. Replace as necessary. If thermostat is okay, replace ECT sensor and retest.

Replace TP sensor and retest.

1. Drain cooling system. Remove and test thermostat. Replace thermostat as necessary. If thermostat is okay, install thermostat and refill cooling system. Go to next step.
2. If any other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0128 is displayed, replace ECM and retest system.

Diagnosis & Repair (Using OBD-II Scan Tool)

1. Check for DTC output besides P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307 or P0308. Go to relevant DTC test as necessary. If no other DTCs are present, go to next step.
2. Check connection of wire harness and connector. Check for disconnection of piping or a break in vacuum hose. Repair as necessary. If okay, go to next step.
3. Check PCV hose connection. If problem exists, repair as necessary. If problem does not exist, go to next step.
4. Remove the spark plug. Check the spark plug type and electrode gap. Gap should be 0.039-0.043" (1.0-1.1 mm), with a maximum of.051" (1.3 mm). Replace plug as necessary. Check spark by disconnecting injector connector. Install spark plug to ignition coil. Ground the spark plug. If spark jumps across electrode gap while engine is being cranked, go to step 7. If spark does not jump, go to next step.
5. Remove the spark plug. Change spark plug. Perform a spark test. Disconnect the injector connector. Install the spark plug to ignition coil. Ground the spark plug. Check that spark jumps across electrode gap while the engine is being cranked. Do not crank engine for more than 5-10 seconds. If spark jumps across electrode gap while engine is being cranked, replace spark plug. If spark does not jump, go to next step.
6. Check the wire harness between ignition coil and ECM (IF terminal) connectors. Disconnect the I1, I2, I3, I4, I5, I6, I7 or I8 ignition coil connector. Disconnect the ECM E4 connector. see scheme 58and see scheme 59. Check the continuity between the wire harness side connectors. See «ECM/IF SIGNAL TERMINAL CONTINUITY CHECK»(ref-151781-S04858522032003022400000) table. Disconnect the E2 or E4 ECM connector. see scheme 60 Check the continuity between the wire harness side connectors. See «ECM/IGT SIGNAL TERMINAL CONTINUITY CHECK»(ref-151781-S42447153512003022400000) table. If all checks are okay, replace ignition coil assembly. If all checks are not okay, repair or replace harness and connector as necessary.
7. Turn the ignition switch ON. Measure the voltage between the terminals of the E2, E3 and E4 connectors. see scheme 61 See «ECM E2, E3 & E4 CONNECTOR VOLTAGE CHECK»(ref-151781-S01836000412003022600000) table. If okay, go to step 10. If not okay, go to next step.
8. Check fuel injectors. Injector volume should be 3.7-4.5 cu. in. per 15 seconds. Difference between each injector should be.6 cu. in. or less. If problem exists, repair as necessary. If problem does not exist, go to next step.
9. Disconnect the injector connectors. see scheme 62 Disconnect the E2 and E4 ECM connectors. see scheme 63 Check the wire harness between the I9, I10, I11, I12, I13, I14, I15 and I16 injector connectors and ECM connectors. Check the continuity between the wire harness side connectors. Check the wire harness between the I9, I10, I11, I12, I13, I14, I15 and I16 injector connectors and IG2 relay. See «INJECTOR/ECM CONTINUITY CHECK»(ref-151781-S06792656162003022600000) table. Remove the INJ fuse from the engine room No. 2 relay block. Check continuity of EFI No. 2 fuse. Disconnect the injector connectors. Remove the IG2 relay from the engine room No. 1 relay block. Check continuity between the wire harness side connectors. See «INJECTOR/IG2 RELAY CONTINUITY CHECK»(ref-151781-S33863720792003022600000) table.
10. If using scan tool, select the active test mode, and operate fuel pump. If not using hand-held tester, connect positive and negative leads from battery to fuel pump connector. Connect wire to the injector and battery for 15 seconds. see scheme 42 Measure the injection volume with a graduated cylinder. Test each injector 2-3 times. Injection volume should be 3.7-4.5 cu in. per 15 seconds. Difference between each injector should be 0.6 cu in. or less. If not to specification, repair or replace as necessary. If to specification, go to next step.
11. Check engine compression. See «BASIC DIAGNOSTIC PROCEDURES»(ref-151770) article. If engine compression is okay, go to next step.
12. Check valve clearance. See «ON-VEHICLE ADJUSTMENTS»(ref-151768) article. If valve clearance is okay, go to next step.
13. Check valve timing. Check for loose or jumping teeth of timing belt. Repair as necessary. If okay, go to next step.
14. Check fuel pressure. See «FUEL SYSTEM»(ref-151784-S08201823932003010800000) in SYSTEM & COMPONENT TESTING article. Repair as necessary. If okay, go to next step.
15. Disconnect the mass airflow sensor connector. Measure the resistance between terminals of mass airflow sensor. See «AIRFLOW SENSOR RESISTANCE CHECK»(ref-151781-S10007002552003022600000) table. see scheme 49and see scheme 50. Reconnect the mass airflow sensor connector. Turn the ignition switch ON. Measure the voltage between terminals No. 2 and 3 of mass airflow sensor when blowing air into the airflow sensor. Voltage should fluctuate. If okay, go to next step. If not okay, replace mass airflow sensor.
16. Measure the resistance between the terminals of the coolant temperature sensor. see scheme 51 Replace coolant temperature sensor as necessary. If okay, check for intermittent problems.

Confirmation Readiness Test

1. For FIRST TRIP PROCEDURE, vehicle must be cold with ambient temperature about between 50-95°F (10-35°C). Intake Air Temperature (IAT) sensor and Engine Coolant Temperature (ECT) sensor should have almost the same value. Clear DTCs by disconnecting the battery terminals or ETCS fuses. Readiness tests will show INCMPL (incomplete). Test drive vehicle in city and freeway traffic. Note the state of readiness tests. They will change to COMPL as the evaluation monitors operate and if the system passes. This procedure may take about 20 minutes or more. Do not shut off the engine as results will be invalid. (Scheme 26)- (Scheme 33).
2. For PASS CONDITION-NO PROBLEM FOUND BY ECM, if the EVAP evaluation monitor shows COMPL, go to NON-CONTINUOUS TEST screen. To get there, go to ADVANCED OBD-II, ONBOARD TESTS, NON-CONTINUOUS TESTS. If all of the tests show PASS, the evaluation monitor has operated and no problem was detected.
3. For FAIL CONDITION-PROBLEM DETECTED BY THE ECM, if the EVAP evaluation monitor shows INCMPL, go to the NON-CONTINUOUS TEST screen. If all tests show PASS, the following may have occurred: EVAP evaluation monitor did not operate, EVAP evaluation monitor did not finish, or ECM withheld judgement. If one or more of the tests show FAIL, EVAP evaluation monitor did operate and ECM detected a problem. Go to CONTINUOUS TESTS screen. This is the only place DTCs are listed for the first trip. DTC listed may not be valid. A second trip is needed to confirm the DTC.
4. For SECOND TRIP PROCEDURE, vehicle must be cold with ambient temperature at about 50-95°F (10-35°C). Go to READINESS TESTS screen. Drive the vehicle according to LA#4 drive cycle (city and freeway driving). Note state of EVAP evaluation monitor. This procedure may take about 20 minutes or more. Do not shut off the engine as results will be invalid. If READINESS TESTS changes to COMPL, the EVAP evaluation monitor has operated. Check for any stored DTCs. If a DTC has been stored, the problem has been detected and confirmed by the ECM. If no DTC was found, the EVAP monitor operated but no problem was detected.

Scheme 26

Scheme 27

Scheme 28

Scheme 29

Scheme 30

Scheme 31

Scheme 32

Scheme 33

Diagnostic Aids

If DTC P0441 (purge flow), P0446 (VSV for CCV or VSV for pressure switching valve), P0451, P0452 or P0453 (evaporative pressure sensor) is output with DTC P0442 or P0456, first troubleshoot DTC P0441, P0446, P0451, P0452 or P0453. If no malfunction is detected, troubleshoot DTC P0442 or P0456 next.

Check if owner found fuel tank cap was loose and tightened it. Check if fuel tank cap was loose when refuelling. If cap was loose, it was the cause of the DTC. If fuel tank cap was not loose or if owner was not sure if it was loose, troubleshoot according to the following procedure.

Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich at the time of the malfunction. When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the vapor pressure sensor.

Diagnosis & Repair (Using Hand-Held Tester)

1. Connect the hand-held tester to the DLC3. Select the ENHANCED OBD2/SYSTEM CHECK/EVAP SYS CHECK (or EVAP LEAK TEST) mode on hand-held tester. Perform EVAP SYS CHECK (or EVAP LEAK TEST). If scan tool detects a leak on the fuel tank side or canister side, go to DTC P0441 Or DTC P0446, steps 2 and 24. If scan tool detects a leak on EVAP system, go to next step.
2. Check that fuel tank cap is genuine Lexus parts. Replace as necessary. If okay, go to next step.
3. Check that fuel tank cap is correctly installed. Replace as necessary. If okay, go to next step.
4. Check fuel tank cap. Replace as necessary. If okay, go to next step.
5. Check filler neck for damage. Replace as necessary. If okay, go to next step.
6. Connect the hand-held tester to the DLC3. Select the ACTIVE TEST mode on the hand-held tester. Disconnect the vacuum hose for the VSV for the EVAP from the charcoal canister. Start the engine. Select ACTIVE TEST mode on hand-held tester. When the VSV for the EVAP is operated by the hand-held tester, check whether the disconnected hose applies suction to your finger. see scheme 89 With VSV ON, disconnected hose applies suction to your finger. With VSV OFF, disconnected hose applies no suction to your finger. If okay, go to step 10. If not okay, go to next step.
7. Check vacuum hose between intake manifold and VSV for EVAP, and VSV for EVAP and charcoal canister. Check that the vacuum hose is connected correctly. Check the vacuum hose for looseness and disconnection. Check the vacuum hose for cracks, hole and damage. Repair as necessary. If okay, go to next step.
8. Check operation of VSV for EVAP by checking that the air flows with difficulty from ports "E" to "F". Apply battery voltage across the terminals. Check that the air flows without resistance from ports "E" to "F". see scheme 90and see scheme 91. Replace as necessary. If okay, go to next step.
9. Check the wire harness between the VSV 2-pin connector for EVAP and ECM connector. Disconnect the V4 VSV 2-pin connector for EVAP. see scheme 92 Disconnect the E2 ECM connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E2 connector terminal PRG. Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or ECM E2 connector terminal PRG and ECM connector E3 terminal E1. see scheme 93 Check the wire harness between the VSV for EVAP and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V4 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 2 and EFI relay terminal No. 3. If continuity is present, replace ECM. If continuity is not present, repair or replace harness or connector.
10. Connect the hand-held tester to the DLC3. Disconnect the vacuum hose for the VSV for the CCV from the charcoal canister. Turn the ignition switch ON and push the hand-held tester main switch ON. Select ACTIVE TEST mode on hand-held tester. Check the VSV operation when it is operated by the hand-held tester. When VSV is ON, air does not flow from port "E" to port "F". When VSV is OFF, air from port "E" flows out through port "F". see scheme 94 If okay, go to step 14. If not okay, go to next step.
11. Check vacuum hose between VSV for CCV and charcoal canister. Repair as necessary. If okay, go to next step.
12. Check operation of VSV for CCV by checking that the air flows from ports "A" to "B". see scheme 95 Apply battery voltage between VSV terminals. Ensure air does not flow from ports "A" to "B". see scheme 96 If okay, go to next step. If not okay, replace VSV for CCV.
13. Check the wire harness between the VSV 2-pin connector for CCV and ECM connector. Disconnect the V3 VSV 2-pin connector for EVAP. see scheme 97 Disconnect the E4 ECM connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E4 connector terminal CCV. Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or ECM E4 connector terminal CCV and ECM connector E3 terminal E1. see scheme 98 Check the wire harness between the VSV for CCV and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V3 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 2 and EFI relay terminal No. 3. If continuity is present, replace ECM. If continuity is not present, repair or replace harness or connector.
14. Connect the hand-held tester to the DLC3. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the ACTIVE TEST mode on the hand-held tester. Check the VSV operation when it is operated by the hand-held tester. If VSV is ON, air from port "E" flows out through port "F". If VSV is OFF, air does not flow from port "E" to port "F". see scheme 99 If okay, go to step 17. If not okay, go to next step.
15. Check operation of VSV for pressure switching valve by checking that air flows with difficulty from ports "E" to "F". see scheme 100 Apply battery positive voltage across the terminals. Check that the air flows from ports "E" to "F". see scheme 101 Replace as necessary. If okay, go to next step.
16. Check the wire harness between the VSV 2-pin connector for pressure switching valve ECM connector. Disconnect the V12 VSV 2-pin connector for EVAP. see scheme 102 Disconnect the E5 ECM connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E5 connector terminal TBP. see scheme 103 Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or ECM E5 connector terminal TBP and ECM connector E3 terminal E1. Check the wire harness between the VSV for pressure switching valve and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V12 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 2 and EFI relay terminal No. 3. If continuity is present, replace ECM. If continuity is not present, repair or replace harness or connector.
17. Check whether hose close to fuel tank has been modified, and check whether there are signs of any accident near fuel tank. see scheme 104 Repair as necessary. If okay, go to next step.
18. Check vacuum hoses between vapor pressure sensor and fuel tank, charcoal canister and VSV for pressure switching valve, and VSV for pressure switching valve and charcoal canister. Repair as necessary. If okay, go to next step.
19. Check vacuum hoses 4, 5, 7 and 8. see scheme 88 Repair or replace as necessary. If okay, go to next step.
20. Check hose and tube between fuel tank and charcoal canister. Check for proper connection of the fuel tank and fuel EVAP pipe, fuel EVAP pipe and fuel tube under the floor, fuel tube under the floor and charcoal canister. Check the hose and tube for cracks, holes and damage. Replace as necessary. If okay, go to next step.
21. Check charcoal canister assembly for cracks, holes and damage. Replace canister as necessary. If okay, go to next step.
22. Turn the ignition switch ON. Measure the voltage between terminals VPTK and EPTK of ECM connector E5. see scheme 105 If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
23. Turn the ignition switch ON. Measure the voltage between terminals PTNK and EPTK of ECM connector E5. Disconnect the vacuum hose from the vapor pressure sensor. Using the MITYVAC (hand-held vacuum pump), apply a vacuum of 1.18 in. Hg (30 mm Hg) to the vapor pressure sensor. see scheme 106 Vacuum applied to vapor pressure sensor must be less than 19.7 in. Hg (500 mm Hg). If voltage is 2.9-3.7 volts with vacuum and 0.5 volts or less without vacuum, go to next step. If not, go to step 25.
24. Disconnect the V11 vapor pressure sensor 3-pin connector. see scheme 107 Disconnect the E5 ECM connector. Check the continuity between the wire harness side connectors. See «VAPOR PRESSURE SENSOR/ECM CONTINUITY CHECK»(ref-151781-S11058979592003022800000) table. see scheme 108 If continuity is to specification, replace vapor pressure sensor assembly. If continuity is not to specification, repair or replace harness and connector. VAPOR PRESSURE SENSOR/ECM CONTINUITY CHECK Terminals No. Specification PTNK (V11-2) - PTNK (E5-25) Continuity E2 (V11-1) - EPTK (E5-32) Continuity VCC (V11-3) - VPTK (E5-27) Continuity PTNK (V11-2) Or PTNK (E5-25) - E1 (E3-7) No Continuity E2 (V11-1) Or EPTK (E5-32) - E1 (E3-7) No Continuity VCC (V11-3) Or VPTK (E5-27) - E1 (E3-7) No Continuity
25. Check fuel tank over fill check vale assembly for cracks or damage. Replace as necessary. If okay, vehicle owner possibly did not install fuel tank cap correctly.

Diagnosis & Repair (OBD-II Scan Tool)

1. Check that fuel tank cap is a Lexus genuine part. Replace as necessary. If okay, go to next step.
2. Check that fuel tank cap is correctly installed. Correctly install fuel tank cap as necessary. If okay, go to next step.
3. Check fuel tank cap for damage. Replace as necessary. If okay, go to next step.
4. Check filler neck for damage. Replace filler pipe as necessary. If okay, go to next step.
5. Check whether hose close to fuel tank has been modified, and check whether there are signs of any accident near fuel tank or charcoal canister. Check for cracks, deformation and loose connection of fuel tank, charcoal canister, fuel tank filler pipe, hoses and tubes around fuel tank and charcoal canister. see scheme 104 Repair as necessary. If okay, go to next step.
6. Check vacuum hoses between vapor pressure sensor and fuel tank, charcoal canister and VSV for pressure switching valve, and VSV for pressure switching valve and charcoal canister. Repair as necessary. If okay, go to next step.
7. Check hose and tube between fuel tank and charcoal canister. Check for proper connection of the fuel tank and fuel evaporation pipe, fuel evaporation pipe and fuel tube under the floor, fuel tube under the floor and charcoal canister. Repair as necessary. If okay, go to next step.
8. Check VSV connector for EVAP, VSV connector for CCV, VSV connector for pressure switching valve and vapor pressure sensor connector for looseness and disconnection. Repair as necessary. If okay, go to next step.
9. Check vacuum hoses 8, 9, 10 and 11. see scheme 88 Repair as necessary. If okay, go to next step.
10. Turn the ignition switch ON. Measure the voltage between terminals VPTK and EPTK ECM connector. see scheme 105 If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, check and replace ECM.
11. Turn the ignition switch ON. Measure the voltage between terminals PTNK and EPTK of ECM connector E5. see scheme 106 Disconnect the vacuum hose from the vapor pressure sensor. Using the MITYVAC (hand-held vacuum pump), apply a vacuum of 1.18 in. Hg (30mm Hg) to the vapor pressure sensor. Vacuum applied to vapor pressure sensor must be less than 19.7 in. Hg (500mm Hg). If voltage is 2.9-3.7 volts, then changes to 0.5 volts with vacuum applied, go to step 13. If not, go to next step.
12. Check the wire harness between the VSV 2-pin connector for pressure switching valve and ECM connector. Disconnect the V12 VSV 2-pin connector for EVAP. see scheme 102 Disconnect the E5 ECM connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E5 connector terminal TBP. Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or ECM E5 connector terminal TBP and ECM connector E3 terminal E1. see scheme 103 Check the wire harness between the VSV for pressure switching valve and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V12 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 2 and EFI relay terminal No. 3. If continuity is present, replace vapor pressure sensor assembly. If continuity is not present, repair or replace harness or connector.
13. Turn the ignition switch ON. Check VSV for EVAP function. Connect jumper wire between terminal PRG of the ECM E2 connector and E1 of ECM E3 connector (ON), then disconnect jumper wire (OFF). When VSV is on, air from port "E" flows out through port "F". When VSV is OFF, air does not flow from port "E" to port "F". see scheme 109 If okay, go to step 16. If not okay, go to next step.
14. Check operation of VSV for EVAP. Check that the air flows with difficulty from ports "E" to "F". see scheme 90 Apply battery voltage across the terminals. Check that air flows without resistance from ports "E" to "F". see scheme 91 If okay, go to next step. If not okay, replace VSV and charcoal canister. Clean vacuum hoses between throttle body and VSV for EVAP, and VSV for EVAP and charcoal canister.
15. Check the wire harness between the VSV 2-pin connector for EVAP and ECM connector. Disconnect the V4 VSV 2-pin connector for EVAP. see scheme 92 Disconnect the ECM E2 connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E2 connector terminal PRG. Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or ECM E2 connector terminal PRG and ECM connector E3 terminal E1. see scheme 93 Check the wire harness between the VSV for EVAP and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V4 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 2 and EFI relay terminal No. 3. If continuity is present, replace ECM. If continuity is not present, repair or replace harness or connector.
16. Turn the ignition switch ON. Connect jumper wire between terminal CCV of ECM connector E4 and terminal E1 of connector E3, then disconnect jumper wire. When VSV is ON, air from port "E" flows out through port "F". When VSV is OFF, air does not flow from ports "E" to "F". see scheme 110 If okay, go to step 19. If not okay, go to next step.
17. Check operation of VSV for CCV by checking that air flows from ports "A" to "B". see scheme 95 Apply battery positive voltage across the terminals. Check that the air does not flow from ports "A" to "B". see scheme 96 If okay, go to next step. If not okay, replace VSV and charcoal canister, and then clean vacuum hose between charcoal canister and VSV for CCV.
18. Check the wire harness between the VSV 2-pin connector for CCV and ECM connector. Disconnect the V3 VSV 2-pin connector for EVAP. see scheme 97 Disconnect the ECM E4 connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E4 connector terminal CCV. Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or E4 connector CCV and ECM connector E3 terminal E1. see scheme 98 Check the wire harness between the VSV for CCV and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V3 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 2 and EFI relay terminal No. 3. If continuity is present, replace ECM. If continuity is not present, repair or replace harness or connector.
19. Turn the ignition switch ON. Connect jumper wire between terminal TBP of the ECM E5 connector and body ground (ON), then disconnect jumper wire (OFF). When VSV is ON, air from port "E" flows out through port "F". When VSV is OFF, air does not flow from port "E" to port "F". see scheme 111 If okay, go to step 22. If not okay, go to next step.
20. Check operation of VSV for pressure switching valve. Check that the air flows with difficulty from ports "E" to "F". see scheme 100 Apply battery positive voltage across the terminals. Check that air flows from ports "E" to "F". see scheme 101 If okay, go to next step. If not okay, replace VSV and charcoal canister, and then clean vacuum hoses between charcoal canister and VSV for pressure switching valve, and VSV for pressure switching valve and fuel tank.
21. Check the wire harness between the VSV 2-pin connector for pressure switching valve and ECM connector. Disconnect the V12 VSV 2-pin connector for EVAP. see scheme 102 Disconnect the E5 ECM connector. Check the continuity between the wire harness side connectors between 2-pin connector terminal No. 1 and ECM E5 connector terminal TBP. see scheme 103 Continuity should be present. Ensure no continuity is present between 2-pin connector terminal No. 1 or terminal TBP E5 connector and connector E3 terminal E1. Check the wire harness between the VSV for pressure switching valve and EFI relay. Inspect EFI No. 2 fuse. Replace as necessary. Disconnect the V12 VSV 2-pin connector. Remove the EFI relay from the engine room No. 2 relay block. Check continuity between wire harness side of 2-pin connector terminal No. 1 and EFI relay terminal No. 3. If continuity is present, replace ECM. If continuity is not present, repair or replace harness or connector.
22. Check fuel tank over fill check valve by disconnecting purge line hose and EVAP line hose from the charcoal canister. Plug the cap to the air drain hose. Apply.58 psi (4 kPa) of pressure to the purge port and check that there is ventilation in the EVAP line. Check if there is anything stuck in the purge line hose and EVAP line hose. If there is nothing stuck in hoses, replace fuel cut off valve and over fill check valve. Reconnect purge line hose and EVAP line hose to charcoal canister. If okay, replace charcoal canister.

1. Turn ignition on. Backprobing connector, measure voltage between terminals VPTK and EPTK at ECM E5 connector. see scheme 105 If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest system. NOTE: DO NOT apply more than 19.7 in. Hg (500mm Hg) of vacuum to vapor pressure sensor.
2. Backprobing ECM harness connector, measure voltage between terminals EPTK and PTNK at ECM E5 connector. see scheme 106 Disconnect vacuum supply hose (hose closest to electrical connector) from vapor pressure sensor. Sensor is mounted on charcoal canister and is located next to fuel tank. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied, and.5 volt or less with 1.2 in. Hg (30mm Hg) of vacuum applied, replace ECM and retest system. If voltage is not as specified, go to next step.
3. Check for an open or short circuit in wiring harness and connectors between vapor pressure sensor and ECM. see scheme 107and see scheme 108. See «VAPOR PRESSURE SENSOR/ECM CONTINUITY CHECK»(ref-151781-S00599051982003022800000) table. See «ENGINE PERFORMANCE»(ref-158977-S13145987782003110400000) in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If wiring is okay, replace vapor pressure sensor and retest system.

1. Check if the stop lights go on and off normally when the brake pedal is operated and released. If okay, go to next step. If not okay, repair stop light circuit.
2. Turn the ignition switch ON. Measure voltage between terminal E1 of ECM E3 connector and terminal STP of ECM E5 connector. see scheme 129 With brake pedal depressed, 7.5-14 volts should be present. With brake pedal released, less than 1.5 volts should be present. If okay, check for intermittent problems. If not okay, go to next step.
3. Disconnect the D2 driver side junction block ECU 18-pin connector. see scheme 127 Disconnect the ECM E5 connector. see scheme 128 Check continuity between the wire harness side connectors. See «DRIVER SIDE JUNCTION BLOCK/ECM CONTINUITY»(ref-151781-S07491208182003030300000) table. If continuity is to specification, check and replace ECM. If continuity is not to specification, repair or replace harness or connector as necessary. DRIVER SIDE JUNCTION BLOCK/ECM CONTINUITY Terminals Specification STPO (D2-12) - STP (E5-4) Continuity STPO (D2-12) Or STP (E5-4) - E1 (E3-7) No Continuity

For diagnosis and repair, see DTC P0504: BRAKE SWITCH "A"/"B" CORRELATION .

If any DTC is set, replace ECM.

Troubleshoot the multiplex communication system. See appropriate MULTIPLEX COMMUNICATIONS SYSTEMS article.

1. Start engine. Read throttle motor current value on the hand-held tester. At idle, if 7 amps or less is present, go to next step. If motor current value is above 7 amps, disconnect the throttle motor connector. At idle, if 7 amps or more are present, go to step 3. With throttle motor connector disconnected, if 7 amps or less is present, go to next step.
2. Disconnect the throttle control motor connector. Measure the resistance between the terminals of throttle control motor terminals No. 1 and 2. see scheme 130 Resistance should be.3-100 ohms at 68°F (20°C). If resistance is to specification, go to next step. If resistance is not to specification, replace throttle body assembly.
3. Disconnect the T2 throttle control motor 2-pin connector. see scheme 131 Disconnect the E2 ECM connector. see scheme 132 Check the continuity between the wire harness side connectors. See «THROTTLE CONTROL MOTOR/ECM CONTINUITY CHECK»(ref-151781-S04215661292003030500000) table. If continuity is to specification, go to next step. If continuity is not to specification, repair or replace harness and connector as necessary.
4. Turn the ignition switch ON. Read the throttle motor current value on the hand-held tester. At idle, current should be 7 amps or less. With accelerator pedal quickly released, current should be.5 amps or more. If okay, check for intermittent problems. If not okay, replace ECM.

THROTTLE CONTROL MOTOR/ECM CONTINUITY CHECK

Scheme 34

1. Connect the oscilloscope between terminals M+ or M- of the ECM E2 connector and E1 of the ECM E3 connector. Start engine. During cranking or idling, check waveform between terminal M+ of ECM E2 connector and terminal E1 of ECM E3 connector, and between terminal M- of ECM E2 connector and terminal E1 of ECM E3 connector. (Scheme 34) If waveforms are okay, go to next step. If waveforms are not okay, replace ECM.
2. Disconnect the throttle control motor connector. Measure the resistance between the terminals of throttle control motor terminals No. 1 and 2. see scheme 130 Resistance should be.3-100 ohms at 68°F (20°C). If resistance is to specification, go to next step. If resistance is not to specification, replace throttle body assembly.
3. Disconnect the T2 throttle control motor 2-pin connector. see scheme 131 Disconnect the ECM E2 connector. Check the continuity between the wire harness side connectors. see scheme 132 See «THROTTLE CONTROL MOTOR/ECM CONTINUITY CHECK»(ref-151781-S04215661292003030500000) table. If continuity is to specification, replace ECM. If continuity is not to specification, repair or replace harness and connector as necessary.

1. Check whether or not a foreign body is caught between the throttle valve and housing. Repair as necessary. If okay, go to next step.
2. Disconnect the throttle control motor connector. Measure the resistance between the terminals of throttle control motor terminals No. 1 and 2. see scheme 130 Resistance should be.3-100 ohms at 68°F (20°C). If resistance is to specification, go to next step. If resistance is not to specification, replace throttle body assembly.
3. Disconnect the T2 throttle control motor 2-pin connector. see scheme 131 Disconnect the ECM E2 connector. Check the continuity between the wire harness side connectors. see scheme 132 See «THROTTLE CONTROL MOTOR/ECM CONTINUITY CHECK»(ref-151781-S04215661292003030500000) table. If continuity is to specification, problem is intermittent. If continuity is not to specification, repair or replace harness and connector as necessary.

1. Check for other DTCs. If other DTCs are output, diagnose those DTCs first. If no other DTCs are output, go to next step.
2. Check whether or not a foreign body is caught between the throttle valve and housing. Clean as necessary. If okay, go to next step.
3. Disconnect the throttle control motor connector. Measure the resistance between the terminals of throttle control motor terminals No. 1 and 2. see scheme 130 Resistance should be.3-100 ohms at 68°F (20°C). If resistance is to specification, go to next step. If resistance is not to specification, replace throttle body assembly.
4. Replace the ECM. Clear DTC. Operating hand held tester, erase codes or disconnect battery terminal or remove EFI and ECTS fuses. Start and warm up the engine. Run engine at idle for 5 minutes or more. Read output DTC using hand-held tester or the OBD-II scan tool. If no DTC is output, system is okay. If DTC is output, replace throttle body.

1. Disconnect the accelerator pedal position sensor connector. Measure the resistance between the terminals of the accelerator pedal position sensor. See «ACCELERATOR PEDAL POSITION SENSOR RESISTANCE»(ref-151781-S40407210692003030500000) table. see scheme 136 If resistance is to specification, go to next step. If resistance is not to specification, replace accelerator pedal rod assembly.
2. Disconnect the A14 accelerator pedal position sensor 6-pin connector. see scheme 137 Disconnect the ECM E5 connector. Check the continuity between the wire harness side connectors. See «ACCELERATOR PEDAL POSITION SENSOR/ECM CONTINUITY CHECK»(ref-151781-S09098340842003030500000) table. see scheme 138 If continuity is to specification, go to next step. If continuity is not to specification, repair or replace harness or connector as necessary.
3. Turn the ignition switch ON. Measure the voltage between the terminals of the ECM E5 connector. See «VPA & VPA2 VOLTAGE CHECK»(ref-151781-S22914630192003030500000) table. see scheme 163 If voltage is to specification, go to next step. If voltage is not to specification, replace ECM.
4. Disconnect the A14 accelerator pedal position sensor 6-pin connector. see scheme 137 Disconnect the ECM E5 connector. Check the continuity between the wire harness side connectors. See «ACCELERATOR PEDAL POSITION SENSOR/ECM CONTINUITY CHECK»(ref-151781-S09098340842003030500000) table. see scheme 138 If continuity is to specification, replace ECM. If continuity is not to specification, repair or replace harness or connector as necessary.

1. Turn ignition on. Using hand-held tester or scan tool, read voltage for accelerator pedal position sensor data. See «ACCELERATOR PEDAL POSITION VOLTAGE CHECK»(ref-151781-S25094233602003110700000) table. If voltages are to specification, replace ECM. If voltages are not to specification, go to next step. ACCELERATOR PEDAL POSITION VOLTAGE CHECK Accelerator Pedal Position VPA VPA2 Released.5-1.1 Volts.9-2.3 Volts Depressed 3-4.6 Volts 3.4-5.5 Volts
2. Disconnect the accelerator pedal position sensor connector. Measure the resistance between the terminals of the accelerator pedal position sensor. see scheme 136 See «ACCELERATOR PEDAL POSITION SENSOR RESISTANCE»(ref-151781-S40407210692003030500000) table. If resistance is to specification, go to next step. If resistance is not to specification, replace accelerator pedal rod assembly.
3. Turn the ignition switch ON. Measure the voltage between the terminals of the ECM E5 connector. See «VPTK & VCPA VOLTAGE CHECK»(ref-151781-S33651497042003030500000) table. see scheme 162 If voltage is to specification, go to next step. If voltage is not to specification, replace ECM.
4. Turn the ignition switch ON. Measure the voltage between the terminals of the ECM E5 connector. See «VPA & VPA2 VOLTAGE CHECK»(ref-151781-S22914630192003030500000) table. see scheme 163 If voltage is to specification, go to next step. If voltage is not to specification, replace ECM.
5. Disconnect the A14 accelerator pedal position sensor 6-pin connector. see scheme 137 Disconnect the ECM E5 connector. Check the continuity between the wire harness side connectors. See «ACCELERATOR PEDAL POSITION SENSOR/ECM CONTINUITY CHECK»(ref-151781-S09098340842003030500000) table. see scheme 138 If continuity is to specification, replace ECM. If continuity is not to specification, repair or replace harness or connector as necessary.