DTC Troubleshooting: P0645 (128-5)

DTC P0645: A/C Clutch Relay Circuit Open

1. Turn the ignition switch ON (II).

1. Clear the DTC with the HDS.

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

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

Is DTC P0645 indicated?

YES | - | Go to Step 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.■

1. Turn the ignition switch OFF.

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

1. Turn the ignition switch ON (II).

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

Is there battery voltage?

YES | - | Go to Step 9 .
NO | - | Repair open in the wire between the A/C clutch relay and the No. 30 IG HAC (30 A) fuse in the under-hood fuse/relay box, then go to Step 14 .

1. Check the A/C clutch relay.

Is the A/C clutch relay OK?

YES | - | Go to Step 10 .
NO | - | Replace the A/C clutch relay, then go to Step 14 .

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

1. Reconnect the A/C clutch relay.

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

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

Is there battery voltage?

YES | - | Go to Step 19 .
NO | - | Repair open in the wire between the A/C clutch relay and ECM connector No. 2 terminal No. 45, then go to Step 14 .

1. Reconnect all connectors.

1. Turn the ignition switch ON (II).

1. Reset the ECM with the HDS.

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

1. 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 Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | Troubleshooting is complete.■

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

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

1. 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 Step 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. ■