DTC P0645: A/C Clutch Relay Circuit: Testing
- Turn ignition on. Using scan tool, actuate A/C clutch relay. Locate A/C clutch relay in Power Distribution Center (PDC). See Fig 1 . If A/C clutch relay is clicking, go to next step. If A/C clutch relay is not clicking, go to step 4 .
- Wiggle wiring harness between A/C clutch relay and PCM while relay is being actuated. If A/C clutch relay stops clicking when wiring harness is being wiggled, repair wiring where wiggling caused A/C clutch relay to stop clicking. If A/C clutch relay does not stop clicking when wiring harness is being wiggled, go to next step.
- Conditions that set DTC are not present at this time. Perform the following to help identify intermittent condition:
- With engine running at normal operating temperature, wiggle related wiring harness while monitoring related parameters on scan tool. If voltage changes or DTC sets while wiggling wiring harness, repair connectors or wiring harness where wiggling caused voltage to change or DTC to set.
- Review freeze frame information on scan tool. Duplicate conditions present when DTC was set.
- Refer to any technical service bulletins that may apply.
- Visually inspect related wiring harness. Check for chafed, pierced, pinched or partially broken wires.
- Visually inspect related wiring harness connectors. Check for broken, bent, pushed out or corroded terminals.
If a problem is found, repair as necessary. If no problems are found, test is complete.
- Turn ignition off. Remove A/C clutch relay from PDC. Turn ignition on. Measure voltage between ground and fused ignition switch output circuit (Light Green/Black wire) at A/C clutch relay harness connector terminal "A". See Fig 1 . If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open in fused ignition switch output circuit. See WIRING DIAGRAMS article.
- Measure resistance of A/C clutch relay coil between A/C clutch relay terminals "A" and "C" . See Fig 2 . If resistance is 60-80 ohms, go to next step. If resistance is not 60-80 ohms, replace A/C clutch relay.
- Ensure ignition is off. Disconnect PCM harness connectors. See Figure . Measure resistance of A/C clutch relay control circuit (Dark Blue/Orange wire) between A/C clutch relay harness connector terminal "C" and terminal No. 64 at PCM C2 harness connector. See Figure and Fig 1 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Dark Blue/Orange wire.
- Measure resistance between ground and A/C clutch relay control circuit (Dark Blue/Orange wire) at A/C clutch relay harness connector terminal "C". If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Dark Blue/Orange wire between A/C clutch relay and PCM.
- If no other possible causes are remaining, PCM is assumed to be defective. Replace PCM.