| 1. | Disconnect the ALT 4P connector. |
| 2. | Turn the ignition switch ON (II). |
| 3. | Measure voltage between ECM/PCM connector terminals A24 and B13.
Is there about 5 V? YES - Go to 4. NO - Go to 14. |
| 4. | Turn the ignition switch OFF. |
| 5. | Reconnect the ALT 4P connector. |
| 6. | Start the engine. Hold the engine at 3,000 rpm (min-1) with no load (in Park or neutral) until the radiator fan comes on, then let it idle. |
| 7. | Measure voltage between ECM/PCM connector terminals A24 and B13.
Does the voltage decrease when the headlights and rear window defogger are turned on? YES - The ALT FR signal is OK.n NO - Go to 8. |
| 8. | Turn the ignition switch OFF. |
| 9. | Disconnect the negative cable from the battery. |
| 10. | Disconnect ECM/PCM connector B (24P). |
| 11. | Disconnect the ALT 4P connector. |
| 12. | Connect the ALT 4P connector terminal No. 4 and body ground with a jumper wire.
|
| 13. | Check for continuity between body ground and ECM/PCM connector terminal B13.
Is there continuity? YES - Test the ALT.n NO - Repair open in the wire between the ECM/PCM (B13) and the ALT.n |
| 14. | Turn the ignition switch OFF. |
| 15. | Disconnect the negative cable from the battery. |
| 16. | Disconnect ECM/PCM connector B (24P). |
| 17. | Check for continuity between body ground and ECM/PCM connector terminal B13.
Is there continuity? YES - Repair short in the wire between the ECM/ PCM (B13) and the ALT.n NO - Substitute a known-good ECM/PCM and recheck. If symptom/indication goes away, replace the original ECM/ PCM.n |