P0645

SYMPTOM
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. Scan Tool Testing and Procedures

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>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-2. Powertrain Verification Test - Ver 2
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 (NGC) POWERTRAIN VERIFICATION TEST VER-2.

3. (F202) FUSED IGNITION SWITCH OUTPUT CIRCUIT





Ignition on, engine not running.
Using a 1 2-volt test light connected to ground, probe the (F202) Fused Ignition Switch Output circuit in the connection.
Does the test light illuminate brightly?
Yes>> Go To 4
No>> Repair the open or short to ground in the (F202) Fused Ignition Switch Output circuit. Check and replace any open fuses. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-2.

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 # 88 15.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-2.

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 (NGC) POWERTRAIN VERIFICATION TEST VER-2.
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 (NGC) POWERTRAIN VERIFICATION TEST VER-2.
No>> Replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-2.