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
- (F942) Fused ignition switch output circuit
- (A917) Fused B+ 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. Component Tests and General Diagnostics
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. (F942) FUSED IGNITION SWITCH OUTPUT CIRCUIT

Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (F942) Fused Ignition Switch Output 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 (F942) Fused Ignition Switch Output circuit. Check and replace any open fuses. Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test




4. (A917) FUSED B+ CIRCUIT

Using a 12-volt test light connected to ground, probe the (A917) Fused B+ circuit in the connection.

Q: Does the test light illuminate brightly?

YES: Go To 5
NO: Repair the open or short to ground in the (A917) Fused B+ 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.

Q: 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 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 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.

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