Diagnosis & Repair Procedure
NOTE:
For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS
article in ELECTRICAL.
NOTE:
Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
- Locate main relay under left side of dash panel, See Figure and Fig 1 . Check main relay operating sound while ignition switch is cycled from LOCK to ON position, then to LOCK position. If operation sound is not heard, go to next step. If operation sound is heard, go to step 6 .
- Turn ignition switch to LOCK position. Remove and inspect condition of main fuse "FI", fuse is located in main fuse box at right side of engine compartment. See Figure . If main fuse "FI" is okay, go to next step. If main fuse "FI" is faulty, check for short in circuits connected to this fuse. If short is found, repair as necessary and retest system for normal operation. If no short is found, replace main fuse "FI" and retest system for normal operation.
- Remove main relay, ensure relay connector terminals are okay. Perform main relay component test. See RELAYS under RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING article. If relay is okay, go to next step. If relay is faulty, replace relay and retest system for normal operation.
- Ensure ignition switch is in LOCK position. Install main relay. Disconnect ECM harness connectors, located under instrument panel, behind glove box. See Figure . Check ECM harness connector for poor, loose, corroded or damaged terminal connections. If connections are okay, go to next step. If connectors are faulty, repair as necessary and retest system for normal operation.
- Turn ignition switch to ON position. Measure voltage between ground and ECM 26-pin harness connectors C51-3 terminals No. 20 (Black/White wire) and ECM 35-pin harness connector E61 terminal No. 9 (Blue wire). See Figure . If voltage is 10-14 volts, go to next step. If voltage is less than 10 volts, repair open circuit in Black/White wire between fuse box and ECM, or in Blue wire between main relay and ECM, or Black/Red wire between main relay and main fuse box. After repair, retest system for normal operation.
- Turn ignition switch to LOCK position. Using a fused jumper wire, ground ECM harness connector E61 terminal No. 9 (Blue wire). Turn ignition switch to ON position. Measure voltage between ground and ECM harness connector C51-3 terminal No. 15 (Blue/Black wire). See Figure . If voltage is less than 10 volts, go to next step. If voltage is 10-14 volts, check ECM grounds for open circuit between ECM and ground points No. 4 (Black/Blue wire) and No. 5 (Black/Green wire). If open circuit is found, repair as necessary and retest system for normal operation. If ground circuits are okay, substitute ECM with a known good unit and retest system for normal operation.
- If operation sound of main relay was heard on step 1 , go to next step. If operation sound of main relay was not heard, repair open circuit in Black/Red wire between main relay and main fuse box, or in Blue/Black wire between main relay and ECM. After repair, retest system for normal operation.
- Remove main relay, ensure relay connector terminals are okay. Perform main relay component test. See RELAYS under RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING article. If relay is faulty, replace relay and retest system for normal operation. If relay is okay, repair open circuit in Black/Red wire between main relay and main fuse box, or in Blue/Black wire between main relay and ECM. After repair, retest system for normal operation.