M/T Model
Alternator FR Signal Circuit TroubleshootingM/T Model
1. Disconnect the alternator 4P connector.
2. Turn the ignition switch ON (II).
3. Measure voltage between ECM connector terminals A19 and A26.
Is there approx. 5 V?
YES - Go to step 4.
NO - Go to step 14.
4. Turn the ignition switch OFF.
5. Reconnect the alternator 4P connector.
6. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on, then let it idle.
7. Measure voltage between ECM connector terminals A19 and A26.
Does the voltage decrease when the headlights and rear defogger are turned on?
YES - The alternator FR signal is OK.
NO - Go to step 8.
8. Turn the ignition switch OFF.
9. Disconnect ECM connector A (31P).
10. Disconnect the alternator 4P connector.
11. Connect alternator 4P connector terminal No.4 to body ground with a jumper wire.
12. Check for continuity between body ground and ECM connector terminal E19.
Is there continuity?
YES - Test the alternator.
NO - Repair open in the wire between the ECM (A19) and the alternator.
13. Turn the ignition switch OFF.
14. Disconnect ECM connector A (31P).
15. Check for continuity between body ground and ECM connector terminal A19.
Is there continuity?
YES - Repair short in the wire between the ECM (A19) and the alternator.
NO - Substitute a known-good ECM and recheck. If voltage is normal, replace the original ECM.