P0647

P0647-A/C CONTROL CIRCUIT HIGH

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

Theory of Operation

The Powertrain Control Module (PCM) receives various information from the operator controls and engine sensor inputs to determine when the A/C Compressor Clutch should be turned on. The Totally Integrated Power Module (TIPM) receives a signal from the PCM to turn on the A/C Compressor Clutch. The A/C Pressure Sensor information is an input to the TIPM. The TIPM uses the A/C Pressure Sensor input signal to determine if the A/C Compressor Clutch should be turned on. 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 Compressor Clutch output does not match the signal from the A/C Compressor Clutch feedback.





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

1. CHECK THE (C13) A/C COMPRESSOR CLUTCH CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the TIPM C1 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 Compressor Clutch Control circuit at the TIPM C1 harness connector.

Is there any voltage present?

Yes

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

No

- Go To 2

2. CHECK THE POWERTRAIN CONTROL MODULE
1. Using a 12-Volt test light connected battery positive, probe the (C13) A/C Compressor Clutch Control circuit at the TIPM C1 harness connector while actuating the A/C Compressor 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 Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE TOTALLY INTEGRATED POWER MODULE
1. Reconnect the TIPM C1 harness connector.
2. Using a back probing tool back probe the (C3) A/C Compressor Clutch Output Control circuit in the TIPM C1 harness connector.
3. Using a 12-Volt test light connected to ground, probe the (C3) A/C Compressor Clutch Output Control at the TIPM C1 harness connector while actuating the A/C Compressor 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.