P0645

P0645-A/C CLUTCH RELAY CIRCUIT

P0645-A/C Clutch Relay Circuit:

WHEN MONITORED
With the ignition on. Battery voltage greater than 10.4 volts.

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.

POSSIBLE CAUSES
- (C28) A/C clutch control circuit shorted to battery voltage
- (C28) A/C clutch control circuit open
- (C28) A/C clutch control circuit shorted to ground
- TIPM
- PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. A/C CLUTCH OPERATION

Ignition on, engine not running.
With a scan tool in the Powertrain Actuators, actuate the A/C Clutch

Q: Is the A/C Clutch 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 CONTROL OPERATION FROM THE PCM

Turn the ignition off.
Disconnect the TIPM C1 harness connector.
Turn the ignition on.
Using the scan tool in the Powertrain Actuators, actuate the A/C Clutch
With a 12-volt test light connected to ground, probe the A/C Clutch Control circuit in the TIPM C1 harness connector.

Q: Does the test light illuminate brightly and flash on and off?

YES:

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

If OK, replace the TIPM. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 3




3. (C28) A/C CLUTCH CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE

Stop the A/C Clutch actuation.
Turn the ignition off.
Disconnect the PCM C3 harness connector.
Turn the ignition on.
Measure the voltage of the (C28) A/C Clutch Control circuit at the TIPM C1 harness connector.

Q: Does the voltmeter indicate voltage present?

YES: Repair the short to voltage in the (C28) A/C Clutch Relay Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
NO: Go To 4




4. (C28) A/C CLUTCH CONTROL CIRCUIT OPEN

Turn the ignition off.

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 (C28) A/C Clutch Control circuit from the TIPM harness connector to the appropriate terminal of special tool #8815.

Q: Is the resistance below 5.0 ohms?

YES: Go To 5
NO: Repair the open in the (C28) A/C Clutch Control circuit. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test




5. (C28) A/C CLUTCH CONTROL CIRCUIT SHORTED TO GROUND

Measure the resistance between ground and the (C28) A/C Clutch Control circuit in the TIPM C1 harness connector.

Q: Is the resistance below 100 ohms?

YES: Repair the short to ground in the (C28) A/C Clutch Control circuit. Perform the 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.

Q: 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