Alternator Control Circuit Troubleshooting

Alternator Control Circuit Troubleshooting

1. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC). Initial Inspection and Diagnostic Overview

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

3. Make sure the HDS communicates with the vehicle and the engine control module (ECM) If it does not communicate, troubleshoot the DLC circuit.. Testing and Inspection

4. Check for DTCs. Initial Inspection and Diagnostic Overview If a DTC is present, diagnose and repair the cause before continuing with this test.

5. Disconnect the alternator 4P connector.

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 ECM from damage.

9. Disconnect ECM connector B (44P).

10. Check for continuity between ECM connector terminal B41 and body ground.

Is there continuity?
YES - Repair short to ground in the wire between alternator 4P connector terminal No. 2 and ECM connector terminal B41.

NO - Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM, Initial Inspection and Diagnostic Overview then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. 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 ECM from damage.

12. Disconnect ECM connector B (44P).

13. Check for continuity between ECM connector terminal B41 and alternator 4P connector terminal No. 2.

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

NO - Repair open in the wire between alternator 4P connector terminal No. 2 and ECM connector terminal B41.