Alternator Control Circuit Troubleshooting

1.Connect the Honda Diagnostic System (HDS) to the data link connector (DLC).

2.Turn the ignition switch ON (II).

3.Make sure the HDS communicates with the vehicle and the ECM/PCM. If it doesn't, troubleshoot the DLC circuit.

4.Check for DTCs. If a DTC is presnt, 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 11.


NO - Go to 8.


8.Jump the SCS line with the HDS, then turn the ignition switch OFF.

NOTE: This step must be done to protect the engine control module (ECM)/powertrain control module (PCM) from damage.

9.Disconnect ECM/PCM connector B (44P).

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

 

Is there continuity?


YES - Repair a short in the wire between the alternator and the ECM/PCM.n


NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n


11.Jump the SCS line with the HDS, then turn the  ignition switch OFF.

NOTE: This step must be done to protect the engine control module (ECM)/powertrain control module (PCM) from damage.

12.Disconnect ECM/PCM connector B (44P).

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

 

Is there continuity?


YES - Replace the alternator, or repair the alternator.n


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