P0645

P0645-A/C CLUTCH RELAY CIRCUIT






For a complete wiring diagram refer to: Electrical Diagrams

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 relay control circuit. One Trip Fault. Three good trips to turn off the MIL.

Possible Causes
- INTERNAL FUSED IGNITION SWITCH OUTPUT CIRCUIT
- (C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN
- (C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO GROUND
- A/C CLUTCH RELAY
- PCM

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.
Perform 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 IPM.
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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
3. INTERNAL FUSED B+ CIRCUIT
Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the Internal 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 Internal Fused B+ circuit. Check and replace any open fuses.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN
Turn the ignition off. Disconnect the PCM harness connectors.

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 5
No >> Repair the open in the (C13) A/C Clutch Relay Control circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (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 IPM.

Is the resistance below 5.0 ohms?
Yes >> Repair the short to ground in the (C13) A/C Relay Clutch Control circuit.
Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Go To 6
6. 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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No >> Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST.Powertrain Verification Test