DTC Troubleshooting: P0647 (128)
DTC P0647:
 A/C Clutch Relay Circuit Shorted to Power
NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.
  1. Turn the ignition switch ON (II).
  1. Clear the DTC with the HDS.
  1. Turn the A/C switch on.
  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 P0647 indicated?
YES -
Go to Step 6 .
NO -
Intermittent failure, the 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 from the under-hood fuse/relay box.
Is the A/C clutch relay OK?
YES -
Go to Step 9 .
NO -
Replace the A/C clutch relay, then go to Step 11 .
  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 -
Repair short to power in the wire between the A/C clutch relay and ECM connector No. 2 terminal No. 45, then go to Step 11 .
NO -
Go to Step 17 .
  1. Reconnect all connectors.
  1. Turn the ignition switch ON (II).
  1. Reset the ECM with the HDS.
  1. Turn the A/C switch on.
  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 P0647 indicated?
YES -
Check for poor connections or loose terminals at the A/C clutch relay and the ECM, then go to Step 1 .
NO -
Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■
  1. Reconnect all connectors.
  1. Turn the A/C switch on.
  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 P0647 indicated?
YES -
Check for poor connections or loose terminals at the A/C clutch relay and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 19 . If the ECM was substituted, go to Step 1 .
NO -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.