Alternator Control Circuit Troubleshooting

Alternator Control Circuit Troubleshooting

NOTE: Do this troubleshooting if, in step 5 of the Alternator and Regulator Circuit Troubleshooting, Alternator and Regulator Circuit Troubleshooting the battery voltage is less than 13.5 V.

1. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC). Reading and Clearing Diagnostic Trouble Codes

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

3. Make sure the HDS communicates with the vehicle and the powertrain control module (PCM). If it doesn't communicate, troubleshoot the DLC circuit. Testing and Inspection

4. Check for DTCs. Reading and Clearing Diagnostic Trouble Codes If a DTC is present, diagnose and repair the cause before continuing with this test.

5. Disconnect the alternator 4P connector from the alternator.

6. Start the engine, and turn on the headlights to high beam.

7. Measure the voltage between alternator 4P connector terminal No. 2 and the positive terminal of the battery.

Is there 1 V or less?
YES - Go to step 11.

NO - Go to step 8.






8. Jump the SCS line with the HDS, then turn the ignition switch to LOCK (0).
NOTE: This step must be done to protect the PCM from damage.

9. Disconnect PCM connector A (31P).

10. Check for continuity between PCM connector terminal A24 and body ground.

Is there continuity?
YES - Repair a short in the wire between the alternator and the PCM.

NO - Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM. Service and Repair






11. Jump the SCS line with the HDS, then turn the ignition switch to LOCK (0).
NOTE: This step must be done to protect the PCM from damage.

12. Disconnect PCM connector A (31P).

13. Check for continuity between PCM connector terminal A24 and alternator 4P connector terminal No. 2.

Is there continuity?
YES - Replace the alternator, Removal and Replacement or repair the alternator. Overhaul

NO - Repair an open in the wire between the alternator and the PCM.