P0645
P0645-A/C CONTROL CIRCUIT/OPEN
For a complete wiring diagram Consult Diagrams/Electrical
- When Monitored:
With the control circuit active and battery voltage greater than 10.4 volts.
- Set Condition:
The PCM detects an open or shorted condition in the (C13) A/C Clutch Relay Control circuit.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview
Diagnostic Test
1. DTC IS ACTIVE
Ignition on, engine not running.
With the scan tool, Clear DTCs in the Powertrain Control Module (PCM).
With the scan tool, actuate the A/C Compressor Clutch Relay Control State.
With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go to 2
No
- REFER TO the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking For An Intermittent DTC
2. INTERNAL FUSED B(+) CIRCUIT OPEN OR HIGH RESISTANCE
Turn the ignition off.
Remove the A/C Clutch Relay.
Turn the ignition on.
Using a 12 volt test light connected to ground, check the Internal Fused B(+) circuit in the A/C Clutch Relay connector.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go to 3
No
- Repair the Internal Fused B(+) circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test.
3. INTERNAL FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT OPEN OR HIGH RESISTANCE
Using a 12 volt test light connected to ground, check the Internal Fused Ignition Switch Output (Run-Start) circuit in the A/C Clutch Relay connector.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Go to 4
No
- Repair the Internal Fused Ignition Switch Output (Run-Start) circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test.
4. (C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
Measure the voltage of the (C13) A/C Clutch Relay Control circuit in the A/C Clutch Relay connector.
Is there any voltage present?
Yes
- Repair the (C13) A/C Clutch Relay Control circuit for a short to voltage.
- Perform the PCM Verification Test.Powertrain Verification Test.
No
- Go to 5
5. (C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Measure the resistance between ground and the (C13) A/C Clutch Relay Control circuit in the A/C Clutch Relay connector.
Is the resistance below 100 ohms?
Yes
- Repair the (C13) A/C Clutch Relay Control circuit for a short to ground.
- Perform the PCM Verification Test.Powertrain Verification Test.
No
- Go to 6
6. (C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
Measure the resistance of the (C13) A/C Clutch Relay Control circuit between the A/C Clutch Relay connector and the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go to 7
No
- Repair the (C13) A/C Clutch Relay Control circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test.
7. A/C CLUTCH RELAY
Connect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
With the scan tool, actuate the A/C Compressor Clutch Relay Control State control to the ON position.
Using a 12 volt test light connected to 12 volts, check the (C13) A/C Clutch Relay Control circuit in the A/C Clutch Relay harness connector.
NOTE: If the DTC is active, the actuation test may not be allowed by the PCM. If may be necessary to clear the DTCs before starting the actuation.
NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test light illuminated and bright?
Yes
- Replace the A/C Clutch Relay.
- Perform the PCM Verification Test.Powertrain Verification Test.
No
- Go to 8
8. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the A/C Clutch Relay and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test.