Honda Accord: Alternator Control Circuit Troubleshooting

NOTE: Do this troubleshooting if, in step 5 of the alternator and regulator circuit troubleshooting (see page 4-27), the battery voltage is less than 13.5 V.

* 1. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC) (see step 2 on page 11-3).

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

3. Make sure the HDS communicates with the vehicle and the engine control module (ECM)/powertrain control module (PCM). If it does not communicate, troubleshoot the DLC circuit (see page 11-181).

4. Check for DTCs (see page 11-3). 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.

ALTERNATOR 4P CONNECTOR

Wire side of female terminals

Is there less than 1 V? 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/PCM from damage.

9. Disconnect ECM/PCM connector B (49P).

10. Check for continuity between ECM/PCM connector terminal B45 and body ground.

ECM/PCM CONNECTOR B (49P)

Terminal side of female terminals

Is there continuity? YES-Repair short to ground in the wire between alternator 4P connector terminal No. 2 and ECM/PCM connector terminal B45. ll NO-Update the ECM/PCM if it does not have the latest software (see page 11-203), or substitute a known-good ECM/PCM (see page 11-7), then recheck.

If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM (see page 11 -204).B 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/PCM from damage.

12. Disconnect ECM/PCM connector B (49P).

13. Check for loose terminal and connectors, then check for continuity between ECM/PCM connector terminal B45 and alternator 4P connector terminal No. 2.

ECM/PCM CONNECTOR i (49P)

Terminal side of female terminals

ALTERNATOR 4P CONNECTOR

Wire side of female terminals

Is there continuity? YES-Replace the alternator (see page 4-32), or repair the alternator (see page 4-34).- NO-Repair open in the wire between alternator 4P connector terminal No. 2 and ECM/PCM connector terminal B45.B