A-3: Pcm Power & Ground Circuit Check/Engine Does Not Start
NOTE:
For PCM terminal identification, see PIN VOLTAGE/CIRCUIT RESISTANCE CHARTS article. For circuit wire colors, see appropriate wiring diagram in WIRING DIAGRAMS article.
- Observe main relay (located in engine compartment relay/fuse block) while ignition is cycled on, then off. See Fig 1 or Fig 2 . If no sound is heard at relay, go to next step. If sound is heard at relay, turn ignition off. Disconnect PCM harness connectors and go to step 6 .
- Ensure ignition is off. Remove main relay. Measure resistance between main relay terminals No. 3 and 4. See Fig 1 or Fig 2 . Resistance should be 70-110 ohms on Esteem, and 79-95 ohms on Swift. If resistance is as specified, go to next step. If resistance is not as specified, replace main relay.
- Check continuity between main relay terminals No. 1 and 2. Continuity should not exist. Apply battery voltage to terminal No. 3, and ground to terminal No. 4, of main relay. Continuity should exist between terminals No. 1 and 2 when energized. If continuity is as specified, go to next step. If continuity is not as specified, replace main relay.
- On Esteem, check LAMP fuse (60-amp). On Esteem and Swift, check FI fuse in engine compartment relay/fuse block. If fuse is blown, check for short to ground and repair as necessary. If fuse is okay, go to next step.
- Turn ignition off. Install main relay. Disconnect PCM harness connectors. Check PCM 22-pin harness connector C23 terminal No. 20 and PCM 26-pin harness connector C21 terminals No. 2, 15 and 19 for poor connection. If poor connection is found, repair as necessary and retest system. If connection is okay, go to next step.
- Turn ignition on. Measure voltage between ground and PCM 22-pin harness connector C23 terminal No. 20. Also measure voltage between ground and PCM 26-pin harness connector C21 terminal No. 19. If readings are 10-14 volts on both circuits, go to next step. If readings are not 10-14 volts on both circuits, check for open circuit in wire between main relay and fuse box (20-amp IG fuse on Esteem, or 15-amp IG. COIL fuse on Swift), open circuit in wire between main relay and PCM, or open circuit between FI fuse and main relay. Repair as necessary.
- Using a fused jumper wire, ground PCM 26-pin harness connector C21 terminal No. 19. Turn ignition on. Measure voltage between ground and PCM 26-pin harness connector C21 terminal No. 2. If reading is 10-14 volts, go to next step. If reading is not 10-14 volts, repair open in wire between FI fuse (15-amp) and main relay, or open in wire between PCM harness connector C21 terminal No. 2 and main relay.
- Check for open circuit between ground and PCM harness connector C21 terminals No. 1, 13 and 26 (PCM ground wires). Repair as necessary. If wires are okay, replace PCM. Retest system.