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 in engine compartment fuse/relay block in left side of engine compartment. See COMPONENT LOCATIONS . Check main relay operating sound while ignition switch is cycled from LOCK to ON position, then to LOCK position. If main relay does not click, go to next step. If main relay clicks, go to step 7.
- Check FI fuse (15-amp), located in engine compartment fuse/relay box. See COMPONENT LOCATIONS . If fuse is okay, go to next step. If fuse is blown, check for short in circuits connected to FI fuse. If problem is found, repair as necessary and replace blown fuse. After repair, retest system for normal operation.
- Turn ignition switch to LOCK position. Remove main relay from fuse/relay box. Check for poor, loose, corroded or damaged main relay socket connections, repair as necessary. Perform main relay component test by measuring resistance between main relay terminals No. 1 and 2. See Fig 1. No continuity should exist. Measure resistance between main relay terminals No. 3 and 4. Resistance should be 70-110 ohms. If continuity and resistance are as specified, go to next step. If continuity and/or resistance are not as specified, replace main relay. After repair, retest system for normal operation.
- Using a fused jumper wire, apply battery voltage to main relay terminal No. 3 and ground to terminal No. 4. While main relay is energized, measure continuity between terminals No. 1 and 2. See Fig 1. If continuity exists, go to next step. If continuity does not exist, replace main relay. After repair, retest system for normal operation.
- Ensure ignition switch is in LOCK position. Install main relay. Disconnect ECM harness connectors. See COMPONENT LOCATIONS . Check ECM harness connectors for poor, loose, corroded or damaged terminal connections. See Figure. If connections are okay, go to next step. If connections are faulty, repair as necessary and retest system for normal operation.
- Measure voltage between ground and ECM harness connector C46 terminal No. 7 (Black/White wire). See Figure. If voltage is 10-14 volts, go to next step. If voltage is less than 10 volts, repair open circuit between fuse/relay box and ECM. After repair, retest system for normal operation.
- Using a fused jumper wire, ground ECM harness connector G04 terminal No. 10 (Brown/White wire). Turn ignition switch to ON position. Measure voltage between ground and ECM harness connector G04 terminal No. 8 (Black/Red wire). See Figure. If voltage is 10-14 volts, check ECM ground circuits (Black/Orange wire and Black wire), repair as necessary. If ground circuits are okay, substitute ECM with a known good unit and retest system for normal operation. If voltage is less than 10 volts, go to next step.
- If main relay operating sound was heard in step 1, go to next step. If main relay operating sound was not heard, check for open circuit in Black/Yellow wire between main relay and main fuse in engine compartment relay/fuse block, or in Black/Red wire between main relay and ECM. If problem is found, repair as necessary. After repair, retest system for normal operation.
- Turn ignition to LOCK position. Remove main relay. Perform main relay component test as tested in steps 3 and 4 . If relay is okay, go to next step. If relay is faulty, replace main relay. After repair, retest system for normal operation.
- Check for open circuit in Black/Yellow wire between main relay and main fuse in engine compartment relay/fuse block, or in Black/Red wire between main relay and ECM. If problem is found, repair as necessary. After repair, retest system for normal operation.