## Idle Control System

#### Alternator FR Signal Circuit Troubleshooting

11-120

1. Disconnect the ALT 4P connector.

2. Turn the ignition switch ON (II).
3. Measure voltage between ECM/PCM connector terminals A24 and B13.

ECM/PCM CONNECTORS

Wire side of female terminals

Is there about 5 V?

YES | - Go to step 4.
NO | - Go to step 14.

4. Turn the ignition switch OFF.
5. Reconnect the ALT 4P 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 ECM/PCM connector terminals A24 and B13.

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

YES | - The ALT FR signal is OK.
NO | - Go to step 8.

8. Turn the ignition switch OFF.
9. Disconnect the negative cable from the battery.
10. Disconnect ECM/PCM connector B (24P).
11. Disconnect the ALT 4P connector.

12. Connect the ALT 4P connector terminal No. 4 and body ground with a jumper wire.

ALT 4P CONNECTOR

Wire side of female terminals

13. Check for continuity between body ground and ECM/PCM connector terminal B13.

ECM/PCM CONNECTOR B (24P)

Wire side of female terminals

Is there continuity?

YES | - Test the ALT (see step 1 on page 4-29).
NO | - Repair open in the wire between the ECM/PCM (B13) and the ALT.

14. Turn the ignition switch OFF.
15. Disconnect the negative cable from the battery.
16. Disconnect ECM/PCM connector B (24P).