Disconnect the ALT 4P connector. Turn the ignition switch ON (II). 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. Turn the ignition switch OFF. Reconnect the ALT 4P connector. 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. 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. Turn the ignition switch OFF. Disconnect the negative cable from the battery. Disconnect ECM/PCM connector B (24P). Disconnect the ALT 4P connector.

Connect the ALT 4P connector terminal No. 4 and body ground with a jumper wire. ALT 4P CONNECTOR Wire side of female terminals 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. Turn the ignition switch OFF. Disconnect the negative cable from the battery. Disconnect ECM/PCM connector B (24P).