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.
Courtesy of DAIMLERCHRYSLER CORPORATION
- Inspect all related wiring and connectors and repair as necessary. Repair wiring and connectors as necessary. If no problems were found with wiring and connectors, go to next step.
- With A/C clutch relay still actuated, wiggle wiring harness from A/C clutch relay to PCM. If wiggling interrupted A/C clutch relay actuation, repair wiring harness as necessary where wiggling caused problem to appear. If wiggling did not interrupt A/C clutch relay actuation, no problem is indicated at this time. Test is complete.
- Turn ignition off. Disconnect A/C clutch relay. Turn ignition on. Measure voltage between ground and terminal "A" (Light Green/Black wire) at A/C clutch relay socket in PDC. See Fig 1. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, check for open in Light Green/Black wire between A/C clutch relay socket and junction block. Junction block is located behind end cover on left side of instrument panel. Repair wiring as necessary. If wiring is okay, check fuse No. 21 (10-amp) in junction block. Replace fuse as necessary.
- Using an ohmmeter, check resistance between terminals "A" and "C" at A/C clutch relay. See Fig 2. If resistance is 50-90 ohms, go to next step. If resistance is not 50-90 ohms, replace A/C clutch relay.
Courtesy of DAIMLERCHRYSLER CORPORATION
- Ensure ignition is off. Disconnect PCM connectors. PCM is located on left side of engine compartment, between Power Distribution Center (PDC) and Transmission Control Module (TCM). See Figure. Inspect connectors for damaged pins, corrosion and loose terminals. Repair connectors as necessary. If connectors are okay, measure resistance of Dark Blue/Orange wire between terminal "C" at A/C clutch relay socket in PDC 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 terminal "C" (Dark Blue/Orange wire) at A/C clutch relay socket in PDC. 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.
- At this time, PCM is assumed to be defective. Replace PCM.