Engine Controls - Self-Diagnostics - Introduction: Diagnosis Lexus RX I

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. The CHECK engine light located on instrument cluster is known as Malfunction Indicator Light (MIL). Inspect MIL to ensure it is operational and will come on if a Diagnostic Trouble Code (DTC) is set.

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 appropriate wiring diagram in WIRING DIAGRAMS article. See «ECM LOCATION»(ref-3915-S33419098472000052400000) .
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-3915-S31229471072000052400000) .

TESTING PROCEDURE

To ensure correct diagnosis and repair, testing should be done in the 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-3915-S31229471072000052400000) .
3. Clear Trouble Codes Clear codes using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-3915-S34745900872000052400000) .
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 appropriate SELF-DIAGNOSTICS article. If no codes are present, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
7. Verification Procedure After repairs have been completed, clear all diagnostic trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-3915-S34745900872000052400000) . Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. 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. Only Lexus scan tool may be used in CHECK mode when retrieving DTCs.

NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). 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. CHECK mode helps determine malfunctions caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when ignition is turned from ON to ACC or OFF position or 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). Apply parking brake. 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 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 article for diagnosis by symptom.
5. If any DTCs are present, perform appropriate circuit test. See appropriate DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION table. For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-3915-S16845358062000052400000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-3915-S37457345012000052400000) under INTRODUCTION.
6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-3915-S34745900872000052400000).

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 by using scan tool and 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.

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - ES300

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - GS300

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - GS400

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - LS400

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION (LX470)

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - RX300

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - SC300

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION - SC400

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. The test drive confirmation test will duplicate the conditions required to set specified DTCs.
2. Test drive confirmation test lists the 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 appropriate SELF-DIAGNOSTICS article.

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 appropriate wiring diagram in WIRING DIAGRAMS article. 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-3915-S06228927252000052400000) table. (Scheme 82) If voltage and resistance readings are not as specified, check wiring circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 82