Alternator FR Signal Circuit Troubleshooting

1.Disconnect the alternator 2P connector.

2.Turn the ignition switch ON (II).

3.Measure voltage between PCM connector terminals A24 and B13.

 


Is there about 5 V?


YES - Go to 4.


NO - Go to 13.


4.Turn the ignition switch OFF.

5.Reconnect the alternator 2P connector.

6.Start the engine. Hold the engine at 3,000 rpm (min-1) with no load (in Park or neutral) until the radiator fan comes on, then let it idle.

7.Measure voltage between PCM connector terminals A24 and B13.

 

Does the voltage decrease when the headlights and rear window defogger are turned on?


YES - The alternator FR signal is OK.n


NO - Go to 8.


8.Turn the ignition switch OFF.

9.Disconnect PCM connector B (24P).

10.Disconnect the alternator 2P connector.

11.Connect the alternator 2P connector terminal No. 2 and body ground with a jumper wire.

 

12.Check for continuity between body ground and PCM connector terminal B13.

 

Is there continuity?


YES - Test the alternator.n


NO - Repair open in the wire between the PCM (B13) and the alternator.n


13.Turn the ignition switch OFF.

14.Disconnect PCM connector B (24P).

15.Check for continuity between body ground and PCM connector terminal B13.

 

Is there continuity?


YES - Repair short in the wire between the PCM (B13) and the alternator.n


NO - Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If the symptom/indication goes away with a known-good PCM, replace the original  PCM.n