DTC Troubleshooting

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. Initial Inspection and Diagnostic Overview

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

6. Turn the ignition switch to LOCK (0).

7. Turn the ignition switch to ON (II).

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

Is DTC P0685 indicated?
YES - Go to step 9.

NO - Intermittent failure, the system is OK at this time.


9. Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview

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

11. Turn the ignition switch to LOCK (0).

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

13. Turn the ignition switch to LOCK (0).

14. Turn the ignition switch to ON (II).

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

Is DTC P0685 indicated?
YES - If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then go to step 10. 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. Service and Repair If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.