DTC Troubleshooting: P0685
DTC P0685: PCM Power Control Circuit/Internal Circuit Malfunction
NOTE:
Before you troubleshoot, review the general troubleshooting information.
If the problem does not return after you clear the DTC, or if this DTC is stored intermittently, check for loose terminals at the FI MAIN RLY OUT line connectors before replacing the PCM.

DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0685 PCM Power Control Circuit/Internal Circuit Malfunction
      

1.
Problem verification:

Problem verification
?1.
Turn the vehicle to the ON mode.

?2.
Clear the DTC with the HDS.


?3.
Start the engine, and let it idle for 30 seconds.

?4.
Turn the vehicle to the OFF (LOCK) mode.

?5.
Turn the vehicle to the ON mode.

?6.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0685 PCM Power Control Circuit/Internal Circuit Malfunction
      

Is DTC P0685 indicated?

     
YES
     
     
     
The failure is duplicated. Update the PCM if it does not have the latest software, or substitute a known-good PCM, then recheck. If DTC P0685 goes away and the PCM was updated, troubleshooting is complete. If DTC P0685 goes away and the PCM was substituted, replace the original PCM.?
     
NO
     
     
     
Intermittent failure. Check the following items. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot.?
PGM-FI main relay 1
PGM-FI main fuse
Poor connections or loose terminals between the PCM and the under-hood fuse/relay box
Poor or loose PCM ground terminals and connections
Poor or loose 12 volt battery cables and connections
Check the 12 volt battery