DTC Troubleshooting: P0645 (128-5)

DTC P0645:  A/C Clutch Relay Circuit Open

1.Turn the ignition switch ON (II).

2.Clear the DTC with the HDS.

3.Do the A/C CLUTCH ON/OFF in the INSPECTION MENU with the HDS.

4.Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0645 indicated?


YES - Go to 5.


NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the A/C clutch relay and the ECM.n


5.Turn the ignition switch OFF.

6.Disconnect the A/C clutch relay in the under-hood fuse/relay box.

7.Turn the ignition switch ON (II).

8.Measure voltage between A/C clutch relay 4P connector terminal No. 3 and body ground.

 

Is there battery voltage?


YES - Go to 9.


NO - Repair open in the wire between the A/C clutch relay and the No. 10 METER (7.5 A) fuse in the under-dash fuse/relay box, then go to 14.

9.Check the A/C clutch relay.

Is the A/C clutch relay OK?


YES - Go to 10.


NO - Replace the A/C clutch relay, then go to 14.


10.Turn the ignition switch OFF, and wait 30 seconds.

11.Reconnect the A/C clutch relay.

12.Disconnect ECM connector No. 2 (58P).

13.Measure voltage between ECM connector No. 2 terminal No. 45 and body ground.

 

Is there battery voltage?


YES - Go to 19.


NO - Repair open in the wire between the A/C clutch relay and ECM connector No. 2 terminal No. 45, then go to 14.

14.Reconnect all connectors.

15.Turn the ignition switch ON (II).

16.Reset the ECM with the HDS.

17.Do the A/C CLUTCH ON/OFF in the INSPECTION MENU with the HDS.

18.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0645 is indicated, check for poor connections or loose terminals at the A/C clutch relay and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Troubleshooting is complete.n


19.Update the ECM if it does not have the latest software, or substitute a known-good ECM.

20.Do the A/C CLUTCH ON/OFF in the INSPECTION MENU with the HDS.

21.Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0645 is indicated, check for poor connections or loose terminals at the A/C clutch relay and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM.n