P0647-A/C CLUTCH CONTROL CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W
- When Monitored:
With the ignition on and the A/C Compressor command on.
- Set Condition:
The ECM detects a short circuit on the (C27) A/C Compressor Control circuit for 0.48 seconds.
| Possible Causes |
| INTERMITTENT DTC |
| (C27) A/C COMPRESSOR CONTROL CIRCUIT SHORTED TO VOLTAGE |
| (C27) A/C COMPRESSOR CONTROL CIRCUIT SHORTED TO THE (K343) FUSED MAIN RELAY OUTPUT CIRCUIT |
| (C27) A/C COMPRESSOR CONTROL CIRCUIT OPEN OR HIGH RESISTANCE |
| A/C COMPRESSOR |
| ENGINE CONTROL MODULE (ECM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. DTC IS ACTIVEIgnition on, engine not running.
With the scan tool, clear DTCs in the Engine Control Module (ECM).
With the scan tool, actuate the A/C Compressor.
Monitor the scan tool for at least two minutes.
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. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
2. (C27) A/C COMPRESSOR CONTROL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the A/C Compressor harness connector.
Disconnect the Engine Control Module (ECM) harness connector.
Remove the Main Relay.
Connect a jumper wire between cavity B7 and cavity B9 of the Main Relay Connector.
Turn the ignition on.
Measure the voltage of the (C27) A/C Compressor Control circuit in the A/C Compressor harness connector.
Is there any voltage present?
Yes
- Repair the (C27) A/C Compressor Control circuit for a short to voltage.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Go to 3
3. (C27) A/C COMPRESSOR CONTROL CIRCUIT SHORTED TO THE (K343) FUSED MAIN RELAY OUTPUT CIRCUIT
Turn the ignition off.
Measure the resistance between the (C27) A/C Compressor Control circuit and the (K343) Fused Main Relay Output circuit in the A/C Compressor harness connector.
Is the resistance above 10.0 ohms?
Yes
- Go to 4
No
- Repair the (C27) A/C Compressor Control circuit for a short to the (K343) Fused Main Relay Output circuit.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
4. (C27) A/C COMPRESSOR CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
Measure the resistance of the (C27) A/C Compressor Control circuit between the A/C Compressor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms?
Yes
- Go to 5
No
- Repair the (C27) A/C Compressor Control circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
5. A/C COMPRESSOR
Connect the Engine Control Module (ECM) harness connector.
Install a known good relay in place of the vehicle's A/C Compressor.
Turn the ignition on.
With the scan tool, Clear DTCs.
With the scan tool, actuate the A/C Compressor.
Monitor the scan tool for at least two minutes.
With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go to 6
No
- Replace the A/C Compressor in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
6. ENGINE CONTROL MODULE (ECM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the A/C Compressor and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Refer to any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
- Replace the Engine Control Module (ECM) in accordance with the Service Information.
- Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)