Circuit Test A-3 - Pcm Power & Ground Circuit Check/Engine No Start
- Observe main relay behind center of instrument panel while ignition switch is cycled ON and OFF. If sound is heard at relay, turn ignition off. Disconnect PCM harness connectors and go to step 5). If no sound is heard, go to next step.
- Turn ignition off. Remove main relay. Using an ohmmeter, ensure continuity exists between relay terminals No. 1 and 3. See Fig 1
. Continuity should not exist between relay terminals No. 2 and 4. Apply battery voltage to terminal No. 1 and ground terminal No. 3. Ensure continuity exists between terminals No. 2 and 4. Replace relay if continuity is not as specified. If relay is okay, go to next step.
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- Ensure 15-amp FI fuse in engine compartment relay/fuse box is okay. If fuse is blown, check for short circuit and repair as necessary. If fuse is okay, go to next step.
- Turn ignition off. Disconnect PCM harness connectors. Reinstall main relay. Turn ignition on. Using a voltmeter, measure voltage between ground and PCM harness connector "C", terminal No. 10 (Blue wire). See Figure
. If reading is 10-14 volts, go to next step. If reading is not as specified, repair open Black/Red wire between 15-amp FI fuse and main relay, or open Blue wire between main relay and PCM. Retest system.
- Using a fused jumper wire, connect PCM harness connector "C", terminal No. 10 (Blue wire) to ground. Turn ignition on. Using a voltmeter, measure voltage between ground and PCM harness connector "C", terminals No. 12 and 13 (Blue/Black wires). If reading is 10-14 volts, go to next step. If reading is not as specified, repair open Black/Red wire between 15-amp FI fuse and main relay, or open Black/Blue wire between PCM and main relay. Retest system.
- Check for open Black/Green, Black/Blue, or Black/Orange wires (PCM ground wires). Repair as necessary. If wires are okay, replace PCM. Retest system.