Alternator Control System Test

Alternator Control System Test (K20A3 engine)

1. Check for proper operation of the ELD by checking the MIL.
2. Disconnect the starter sub-harness 8P connector.
3. Start the engine, and turn the headlights (high beam) ON.




4. Measure voltage between the starter sub-harness 8P connector terminal No.3 and the positive terminal of the battery.

Is there 1 V or less?

YES - Go to step B.

NO - Go to step 5.

5. Turn the headlights and ignition switch OFF.
6. Disconnect ECM/PCM connector B (24P).




7. Check for continuity between ECM/PCM connector terminal B18 and body ground.

Is there continuity?

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

NO - Substitute a known-good ECM/PCM, and recheck.

If prescribed voltage is now available, replace the original ECM/PCM.

8. Turn the headlights and ignition switch OFF.
9. Disconnect ECM/PCM connector B (24P).




10. Check for continuity between ECM/PCM connector terminal B18 and starter sub-harness BP connector terminal No.3.

Is there continuity?

YES - Repair the alternator.

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


Alternator Control System Test (K20A2 engine)

1. Check for proper operation of the ELD by checking the MIL.
2. Disconnect the starter sub-harness 6P connector.
3. Start the engine, and turn the headlights (high beam) ON.




4. Measure voltage between the starter sub-harness 6P connector terminal No.2 and the positive terminal of the battery.

Is there 1 V or less?

YES - Go to step 8.

NO - Go to step 5.

5. Turn the headlights and ignition switch OFF.
6. Disconnect ECM connector B (24P).




7. Check for continuity between ECM connector terminal B18 and body ground.

Is there continuity?

YES - Repair short in the wire between the alternator and ECM.

NO - Substitute a known-good ECM, and recheck.

If prescribed voltage is now available, replace the original ECM.

8. Turn the headlights and ignition switch OFF.
9. Disconnect ECM connector B (24P).




10. Check for continuity between ECM connector terminal B18 and starter sub-harness 6P connector terminal No.2.

Is there continuity?

YES - Repair the alternator.

NO - Repair open in the wire between the alternator and ECM.