P0645

P0645-A/C CLUTCH RELAY CIRCUIT

P0645-A/C Clutch Relay Circuit:

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.

Q: 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 IPM.
Measure the resistance of the A/C Clutch Relay Coil.

Q: 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. 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.

Q: 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 the 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.

Q: 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 the 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.

Q: 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 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