Engine Control System Self-Diagnostics - Introduction: Diagnosis Toyota Sienna I

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. CHECK engine light, located on instrument cluster, is referred to 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 comes on, go to next step. 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-3290-S08070929692000042000000) .
2. Start engine and ensure MIL goes off. If MIL goes off, no malfunction is detected at this time. If MIL remains on or blinks with engine running, a malfunction is detected. Proceed to «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-3290-S01206402142000042000000) .

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 scan tool to Data Link Connector No. 3. Retrieve codes and record any freeze-frame data (if applicable). See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-3290-S01206402142000042000000) .
3. Clear Trouble Codes - Clear codes and freeze frame data. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-3290-S27048352252000042000000) .
4. 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. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-3290-S01206402142000042000000) .
6. Diagnose & Repair Diagnostic Trouble Codes - Perform diagnosis and repair procedures as necessary. 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-3290-S27048352252000042000000) . 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 Toyota hand-held tester or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Toyota hand-held tester or OBD-II scan tool may be operated in NORMAL mode when retrieving trouble codes. Only Toyota hand-held tester 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 during 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 Toyota hand-held tester, when ignition switch 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 have been recorded.

CLEARING DIAGNOSTIC TROUBLE CODES

1. After performing repairs, clear Engine Control Module (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.
2. DTCs and freeze-frame data may also be cleared by removing EFI fuse from fuse block 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 cleared 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 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 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-3290-S40965548912000042000000) table. (Scheme 216) 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 216