Diagnostic Routine B

Diagnostic Routine B

Diagnostic Overview

P0645:00

Refer to Wiring Diagram Set 54 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

Voltage is provided to the A/C (Air Conditioning) clutch relay coil. When A/C (Air Conditioning) is requested and A/C (Air Conditioning) line pressures allow, a ground is provided to the A/C (Air Conditioning) clutch relay coil from the PCM (Powertrain Control Module), energizing the A/C (Air Conditioning) clutch relay.

DTC Fault Trigger Conditions






Visual Inspection and Diagnostic Pre-checks

- Inspect BJB (Battery Junction Box) fuse 70 (10A).

- Inspect the PCM (Powertrain Control Module) wiring, terminals or connectors.

- Inspect for loose or corroded PCM (Powertrain Control Module) connections.

- Inspect the A/C (Air Conditioning) clutch relay.

Pinpoint Test

1. CHECK THE VOLTAGE TO THE A/C (Air Conditioning) CLUTCH RELAY

1. Ignition OFF.

2. Disconnect: A/C (Air Conditioning) Clutch Relay.

3. Ignition ON.

4. Measure:





Is the voltage greater than 11 volts?








2. CHECK THE A/C (Air Conditioning) CLUTCH RELAY

1. Carry out the Relay - Ultra Micro ISO (International Organization for Standardization) component test on the A/C (Air Conditioning) clutch relay.

Did the relay pass the component test?








3. CHECK THE A/C (Air Conditioning) CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE

1. Ignition OFF.

2. Disconnect: PCM (Powertrain Control Module) C175B (3.5L) or C1381B (2.0L).

3. Ignition ON.

4. 3.5L engine, measure:





5. 2.0L engine, measure:





Is any voltage present?








4. CHECK THE A/C (Air Conditioning) CLUTCH RELAY COIL SWITCHED GROUND CIRCUIT FOR A SHORT TO GROUND

1. Ignition OFF.

2. 3.5L engine, measure:





3. 2.0L engine, measure:





Is the resistance greater than 10,000 ohms?








5. CHECK THE A/C (Air Conditioning) CLUTCH RELAY COIL SWITCH GROUND CIRCUIT FOR AN OPEN

1. 3.5L engine, measure:





2. 2.0L engine, measure:





Is the resistance less than 3 ohms?








6. CHECK FOR CORRECT PCM (Powertrain Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect all PCM (Powertrain Control Module) connectors.

3. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

4. Reconnect the PCM (Powertrain Control Module) connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?