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-Ohm Meter (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 main fuse/relay block in left side of engine compartment. See Figure . 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 main fuse box. See Figure . 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 block. Check for poor, loose, corroded or damage main relay socket connections. If relay connection is faulty, repair as necessary and retest system for normal operation. If relay connection is okay, perform main relay component test by measuring resistance between main relay terminals No. 1 and 2. See Fig 1 . No continuity should exist. Also measure resistance between main relay terminals No. 3 and 4. Resistance should be 79-95 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 fuse jumper wires, 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 exist, 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 (PCM) harness connectors, located under instrument panel, behind glove box. See Figure . Check ECM (PCM) 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 (PCM) 26-pin harness connectors C51-3 terminals No. 20 (Black/White wire) and ECM (PCM) 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/relay box and ECM (PCM) or Blue wire between main relay and ECM (PCM) 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 (PCM) harness connector E61 terminal No. 9 (Blue wire). Turn ignition switch to ON position. Measure voltage between ground and ECM (PCM) 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 (PCM) grounds for open circuit in Black/Orange wire and Black/Green wire between ECM (PCM) and ground points No. 3 and 5. If open circuit is found, repair as necessary and retest system for normal operation. If ground circuits are okay, substitute ECM (PCM) with a known good unit and retest system for normal operation.
- Turn ignition switch to LOCK position. If main relay operating sound was heard in step 1 , go to next step. If main relay operating sound was not heard, repair open circuit in Black/Red wire between main relay and FI fuse in main fuse box, or in Blue/Black wire between main relay and ECM (PCM). 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 faulty, replace main relay. After repair, retest system for normal operation. If relay is okay, repair open circuit in Black/Red wire between main relay and FI fuse in main fuse box, or in Blue/Black wire between main relay and ECM (PCM). After repair, retest system for normal operation.