Normal Operation

Under normal operation, voltage is provided to the A/C clutch relay coil through circuit 391 (RD/YE). When A/C is requested, and A/C line pressures allow, a ground is provided to the A/C clutch relay coil from the PCM through circuit 73 (OG/LB), energizing the A/C clutch relay.

• DTC P0645 - A/C Clutch Relay Control Circuit - The DTC sets when the PCM grounds the relay circuit, excessive current draw is detected on the relay circuit or, with the relay circuit not grounded by the PCM, voltage is not detected on the relay circuit the PCM expects to detect voltage coming through the relay coil to the relay circuit.

This pinpoint test is intended to diagnose the following:

• Wiring, terminals or connectors
• A/C clutch relay
• PCM