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P0645-A/C CLUTCH CONTROL CIRCUIT
For a complete wiring diagramRefer to Section 8W.
Page 3 of 5267

When Monitored:
With the ignition on. Battery voltage greater than 10 volts. A/C Switch on.
Set Condition:
An open or shorted condition is detected in the A/C clutch control circuit.One Trip Fault. Three good trips to
turn off the MIL.
Possible Causes
(C13) A/C CLUTCH CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
(C13) A/C CLUTCH CONTROL CIRCUIT OPEN
(C13) A/C CLUTCH CONTROL CIRCUIT SHORTED TO GROUND
TIPM
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.A/C CLUTCH OPERATION
Ignition on, engine not running.
With a scan tool, actuate the A/C Clutch.
Is the A/C Clutch actuating?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.(C13) A/C CLUTCH CONTROL CIRCUIT SHORTED TO VOLTAGE
Stop the A/C Clutch actuation.
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (C13) A/C Clutch Control circuit at the C2
TIPM harness connector.
Does the voltmeter indicate voltage present?
Ye s>>
Repair the short to voltage in the (C13) A/C Clutch Control
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
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3.(C13) A/C CLUTCH CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the C3 PCM harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller Special Tool #8815
to perform diagnosis.
Measure the resistance of the (C13) A/C Clutch Control circuit from the
C2 TIPM harness connector to the appropriate terminal of special tool
#8815.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 4
No>>
Repair the open in the (C13) A/C Clutch Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
4.(C13) A/C CLUTCH CONTROL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (C13) A/C Clutch Con-
trol circuit at the C2 TIPM harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the short to ground in the (C13) A/C Clutch Control
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
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5.A/C CLUTCH CONTROL OPERATION FROM THE PCM
Turn the ignition off.
Connect the C3 PCM harness connector.
Ignition on, engine not running.
Using the scan tool in the PCM, actuate the A/C Clutch.
With a 12-volt test light connected to ground, probe the (C13) A/C
Clutch Control circuit in the TIPM C2 harness connector.
Does the test light illuminate brightly and flash on an off?
Ye s>>
NOTE: Before continuing, check the TIPM harness connector ter-
minals for corrosion, damage, or terminal push out. Repair as nec-
essary.
If OK, replace the TIPM in accordance with the Service Information.
No>>
Go To 6
6.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 53 of 5267
P1272-A/C CLUTCH CONTROL CIRCUIT 2 LOW
For a complete wiring diagramRefer to Section 8W.
Page 54 of 5267

When Monitored:
With the ignition on. Battery voltage greater than 10 volts. A/C Switch on.
Set Condition:
A shorted condition is detected in the A/C clutch relay control circuit. One Trip Fault. Three good trips to turn
off the MIL.
Possible Causes
(C3) A/C COMPRESSOR CLUTCH CONTROL CIRCUIT SHORTED TO GROUND
A/C COMPRESSOR CLUTCH
TIPM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.A/C COMPRESSOR CLUTCH OPERATION
Ignition on, engine not running.
With a scan tool under the PCM Actuators, actuate the A/C Clutch.
Is the A/C Clutch actuating?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.A/C CLUTCH CONTROL OPERATION FROM THE PCM
Turn the ignition off.
Disconnect the C2 TIPM harness connector.
Ignition on, engine not running.
Using the scan tool under the PCM Actuators, actuate the A/C Clutch.
With a 12-volt test light connected to ground, probe the (C13) A/C
Clutch Control circuit in the C2 TIPM harness connector.
Does the test light illuminate brightly and flash on an off?
Ye s>>
Go To 3
No>>
Perform the Diagnostic Procedure for P0645-A/C CLUTCH
CONTROL CIRCUIT. (Refer to 9 - ENGINE - DIAGNOSIS
AND TESTING)
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3.(C3) A/C CLUTCH CONTROL OUTPUT CIRCUIT SHORTED TO GROUND
Turn the ignition off
Disconnect the C9 TIPM harness connector.
Disconnect the A/C Compressor Clutch harness connector.
Measure the resistance between ground and the (C3) A/C Clutch Con-
trol Output circuit at the A/C Compressor Clutch harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (C3) A/C Clutch Control
Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
4.A/C COMPRESSOR CLUTCH
Connect the C2 and C9 TIPM harness connectors.
Ignition on, engine not running.
Using the scan tool under the TIPM Actuators, actuate the A/C Clutch.
With a 12-volt test light connected to ground, probe the (C3) A/C Clutch
Control Output circuit at the A/C Compressor Clutch harness connector.
Does the test light illuminate brightly and flash on and off?
Ye s>>
Replace the A/C Compressor Clutch per Service Informa-
tion.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.TOTALLY INTEGRATED POWER MODULE
NOTE: Before continuing, check the TIPM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors.
Pay particular attention to all Power and Ground circuits.
Were any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace the Totally Integrated Power Module per Service Information.
Perform the BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES - STANDARD PROCEDURE)
Page 56 of 5267
P1273-A/C CLUTCH CONTROL CIRCUIT 2 HIGH
For a complete wiring diagramRefer to Section 8W.