P0645

P0645-A/C CLUTCH CONTROL CIRCUIT





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

With the ignition on. Battery voltage greater than 10 volts. A/C Switch on.

- Set Condition:

An open or shorted condition is detected in the A/C clutch control circuit. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. A/C CLUTCH RELAY OPERATION

Ignition on, engine not running.

With a scan tool, actuate the A/C Clutch Relay.

Is the A/C Clutch Relay operating?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 2

2. A/C CLUTCH RELAY RESISTANCE

Turn the ignition off.

Remove the A/C Clutch Relay from the PDC.

Measure the resistance of the A/C Clutch Relay Coil.

Is the resistance between 60 to 80 ohms?

Yes

- Go To 3

No

- Replace the A/C Clutch Relay.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

3. FUSED B+ CIRCUIT





Using a 12-volt test light connected to ground, probe the Fused B+ circuit in the connection.

Does the test light illuminate brightly?

Yes

- Go To 4

No

- Repair the open or short to ground in the Fused B+ circuit. Check and replace any open fuses.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. (F1) FUSED IGNITION SWITCH OUTPUT CIRCUIT





Ignition on, engine not running.

Using a 12-volt test light connected to ground, probe the (F1) Fused Ignition Switch Output circuit in the connection.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Repair the open or short to ground in the (F1) Fused Ignition Switch Output circuit. Check and replace any open fuses.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. (C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN





Turn the ignition off.

Disconnect the C3 PCM harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (C13) A/C Clutch Relay Control circuit from the relay connection to the appropriate terminal of special tool #8815.

Is the resistance below 5.0 ohms?

Yes

- Go To 6

No

- Repair the open in the (C13) A/C Clutch Relay Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

6. (C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO GROUND





Measure the resistance between ground and the (C13) A/C Clutch Relay Control circuit at the PDC.

Is the resistance below 5.0 ohms?

Yes

- Repair the short to ground in the (C13) A/C Relay Clutch Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 7

7. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test