P0645

P0645-A/C CLUTCH RELAY CIRCUIT





For a complete wiring diagram, refer to the Wiring Information.

Theory of operation

The Powertrain Control Module (PCM) receives a signal requesting the A/C Compressor to be turned on from the HVAC. When the PCM receives this request it grounds the control side of the relay.

- When Monitored:
With the ignition on. Battery voltage greater than 10.0 Volts. A/C is being requested.

- Set Condition:
An open or shorted condition is detected in the A/C Clutch Relay control circuit. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. DTC IS ACTIVE

NOTE: If there are any ASD/Main Relay or system voltage DTCs present, diagnose those DTCs before proceeding with this test procedure.

1. Ignition on, engine not running.
2. With the scan tool, select View DTCs. Copy DTC and Freeze Frame information and clear DTCs.

NOTE: Active or pending DTCs may not allow A/C clutch actuation, make sure all DTCs are cleared before proceeding with this test procedure.

3. With the scan tool, actuate the A/C Compressor.
4. Monitor the scan tool for at least two minutes.
5. With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. A/C CLUTCH RELAY
1. Turn the ignition off.
2. Install a know good relay in place of the existing A/C Clutch Relay.
3. Using a scan tool, erase the DTC.
4. Start the engine and and turn the A/C on.

Does the DTC return?

Yes

- Go To 3

No

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

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




1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between ground and the (C13) A/C Clutch Relay Control circuit in the PCM C1 harness connector.

Is the resistance below 100 Ohms?

Yes

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

No

- Go To 4

4. (C13) A/C CLUTCH CONTROL CIRCUIT OPEN OR HIGH RESISTANCE BETWEEN THE PCM AND RELAY
1. Measure the resistance of the (C13) A/C Clutch Control circuit between PCM C1 harness connector and the A/C Clutch Control circuit terminal of the A/C Clutch Relay.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Replace the PDC for an open.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Body Control Module (BCM) and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related connectors.
4. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

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

No

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