## Alternator FR Signal Circuit Troubleshooting

1. | Disconnect the alternator 2P connector.

2. | Turn the ignition switch ON (II).

3. | Measure voltage between PCM connector terminals A24 and B13. Is there about 5 V? YES - Go to 4. NO - Go to 13.

4. | Turn the ignition switch OFF.

5. | Reconnect the alternator 2P 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 PCM connector terminals A24 and B13. Does the voltage decrease when the headlights and rear window defogger are turned on? YES - The alternator FR signal is OK.n NO - Go to 8.

8. | Turn the ignition switch OFF.

9. | Disconnect PCM connector B (24P).

10. | Disconnect the alternator 2P connector.

11. | Connect the alternator 2P connector terminal No. 2 and body ground with a jumper wire.

12. | Check for continuity between body ground and PCM connector terminal B13. Is there continuity? YES - Test the alternator.n NO - Repair open in the wire between the PCM (B13) and the alternator.n

13. | Turn the ignition switch OFF.

14. | Disconnect PCM connector B (24P).

15. | Check for continuity between body ground and PCM connector terminal B13. Is there continuity? YES - Repair short in the wire between the PCM (B13) and the alternator.n NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM.n