Alternator Control Circuit Troubleshooting
Alternator Control Circuit Troubleshooting1. Check for proper operation of the electrical load detector (ELD) by checking for a DTC. If a DTC is present, diagnose and repair the cause before continuing with this test.
NOTE: The ELD DTC does not turn on the MIL.
2. Disconnect the alternator 4P connector from the alternator.
3. Start the engine, and turn on the headlights to high beam.
4. 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 10.
NO - Go to step 5.
5. Turn off the headlights.
6. Turn the ignition switch OFF.
7. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC). Turn the ignition switch ON (II), and 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.
8. Disconnect ECM/PCM connector B (24P).
9. Check for continuity between ECM/PCM connector terminal B18 and body ground.
Is there continuity?
YES - Repair a short to ground in the wire between the alternator and the ECM/PCM (B18).
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.
10. Connect the HDS to the DLC. Turn the ignition switch ON (II), and jump the SCS line with the HDS, then turn the ignition switch OFF.
NOTE: This step must be done to protect the ECM/PCM from damage.
11. Disconnect ECM/PCM connector B (24P).
12. Check for continuity between ECM/PCM connector terminal B18 and alternator 4P connector terminal No. 2.
Is there continuity?
YES - Replace the alternator, or repair the alternator.
NO - Repair an open in the wire between the alternator and the ECM/PCM (B18).