DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P0685

DTC P0685 : ECM Power Control Circuit/Internal Circuit Malfunction

NOTE:
* Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information How To Troubleshoot The Fuel And Emissions Systems.
* If the problem doesn't return after you clear the DTC, or if this DTC is stored intermittently, check for loose terminals at the IGP line connectors before replacing the ECM.

1. Problem verification:

Problem verification
-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

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

-4. Turn the ignition switch to LOCK (0).

-5. Turn the ignition switch to ON (II).

-6. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0685 indicated?
-YES- The failure is duplicated. Update the ECM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM Service and Repair, then do the repair verification.
-NO- Intermittent failure. Check the following items:
* PGM-FI main relay 1
* PGM-FI main fuse
* Poor connections or loose terminals between the ECM and the under-hood fuse/relay box
* Poor or loose ECM ground terminals and connections
* Poor or loose battery cables and connections
* Check the battery

Repair verification:

-1. Start the engine, and let it idle for 30 seconds.

-2. Turn the ignition switch to LOCK (0).

-3. Turn the ignition switch to ON (II).

-4. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0685 indicated?
-YES- If the ECM was updated, substitute a known-good ECM Service and Repair, then recheck. If the ECM was substituted, go to step 1.
-NO- Troubleshooting is complete. If the ECM was substituted, replace the original ECM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.