P0647

P0647-A/C CONTROL CIRCUIT HIGH







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. Turn the ignition off.
2. Reconnect the TIPM C1 harness connector.

NOTE: Be careful to use only an appropriate backprobing tool so as not to damage the terminal or connector in the next step.

3. Using a 12-Volt test light connected to battery positive, backprobe the (C13) A/C Compressor Clutch Control circuit at the TIPM C1 harness connector while toggling the A/C Compressor Clutch with the scan tool.
4. Turn the ignition on, engine not running.
5. Compare the brightness to that of a direct connection to the Battery.

Does the test light toggle on when the A/C Compressor Clutch is on and go off when the A/C Compressor Clutch is toggled off?

Yes

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

No

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.