Alternator Control System Test
NOTE:
After troubleshooting, perform the engine control module (ECM) idle learn procedure (see ECM IDLE LEARN PROCEDURE
).
- Check for proper operation of the electrical load detector (ELD) by checking the malfunction indicator lamp (MIL) (see GENERAL TROUBLESHOOTING INFORMATION ). If a DTC is present, diagnose and repair the cause before continuing with this test.
- Disconnect the engine wire harness 6P connector from the starter sub harness 6P connector.
- Start the engine, and turn the headlights (high beam) ON.
- Measure voltage between the engine wire harness 6P connector terminal No. 2 and the positive terminal of the battery.Fig 1: Measuring Voltage Between The Engine Wire Harness 6P Connector Terminal No. 2 And The Positive Terminal Of The Battery
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there 1 V or less?
YES: Go to step 5.
NO: Go to step 5.
- Turn the headlights and ignition switch OFF.
- Disconnect ECM connector B (24P).
- Check for continuity between ECM connector terminal B18 and body ground.
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Is there continuity?
YES: Repair a short to ground in the wire between the alternator and the ECM.
NO: Check that the terminals are firmly seated at the ECM connector B. If OK, update the ECM if it does not have the latest software or substitute a known-good ECM and recheck. See ECM UPDATING AND SUBSTITUTION FOR TESTING . If prescribed voltage is now available, replace the original ECM (see HOW TO REMOVE THE ECM FOR TESTING ).
- Turn the headlights and ignition switch OFF.
- Disconnect ECM connector B (24P).
- Check for continuity between ECM connector terminal B18 and engine wire harness 6P connector terminal No. 2.Fig 3: Checking For Continuity Between ECM Connector Terminal B18 And Engine Wire Harness 6P Connector Terminal No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES: Repair or replace the starter subharness or the alternator (see ALTERNATOR OVERHAUL ).
NO: Repair an open in the wire between the alternator and the ECM.