P0647

P0647-A/C CONTROL CIRCUIT HIGH





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The Engine Control Module (ECM) receives various information from the operator controls and A/C system to determine when the A/C Compressor clutch should be turned on. The TIPM receives a signal from the ECM to turn on the A/C Compressor clutch. The TIPM supplies 12-volts to the A/C compressor clutch which has a dedicated ground circuit. You will not receive a MIL lamp for this fault, but the customer may complain of poor A/C performance.

- When Monitored:
When the ignition is on.

- Set Condition:
When the signal from the A/C Clutch output does not match the signal from the A/C Clutch feedback.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. (C13) A/C CLUTCH CONTROL CIRCUIT SHORTED TO EXTERNAL VOLTAGE




1. Turn the ignition off.
2. Disconnect the TIPM C2 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Turn the ignition on, engine not running.
4. Using a Voltmeter, measure the voltage on the (C13) A/C Clutch Control circuit at the TIPM harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (C13) A/C Clutch Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 2

2. ENGINE CONTROL MODULE (ECM)




1. Using a 12-volt test light connected battery positive, probe the (C13) A/C Clutch Control circuit at the TIPM connector while actuating the A/C Clutch with the scan tool.

NOTE: The test light must illuminate brightly.

2. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Go To 3

No

- Replace the Engine Control Module (ECM).
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. TOTALLY INTEGRATED POWER MODULE (TIPM)
1. Reconnect the TIPM C2 harness connector.
2. Using a back probing tool 6801, back probe the A/C clutch power circuit in the TIPM C9 harness connector.
3. Using a 12-volt test light connected to ground, probe C3 A/C Clutch Output Control at the TIPM C9 harness connector while actuating the A/C Clutch Circuit with the scan tool.

NOTE: The test light must illuminate brightly.

4. Compare the brightness to that of a direct connection to the battery.

Does the test light illuminate brightly?

Yes

- Test complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Totally Integrated Power Module (TIPM).
- Perform the BODY VERIFICATION TEST. Body Verification Test.