Alternator Control Circuit Troubleshooting

Alternator Control Circuit Troubleshooting

1. Remove the engine compartment covers. Service and Repair

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

3. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.

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

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

6. Disconnect the alternator 4P connector.

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

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

Is there less than 1 V?
YES - Go to step 12.

NO - Go to step 9.






9. Jump the SCS line with the HDS, then turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
NOTE: This step must be done to protect the PCM from damage.

10. Disconnect PCM connector C (49P).

11. Check for continuity between PCM connector terminal C43 and body ground.

Is there continuity?
YES - Repair short to ground in the wire between alternator 4P connector terminal No. 2 and PCM connector terminal C43.

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






12. Jump the SCS line with the HDS, then turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
NOTE: This step must be done to protect the PCM from damage.

13. Disconnect PCM connector C (49P).

14. Check for loose terminals and connectors, then check for continuity between PCM connector terminal C43 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 PCM connector terminal C43.






15. Install the engine compartment covers. Service and Repair