P0686

DTC P0686

Circuit Description
The engine control module (ECM) main relay is energized when the ECM receives an ignition switch ON signal. If the ECM detects the ECM main relay has been ON since the ignition switch was turned OFF, this DTC will set.

Condition for Running the DTC
- The ignition switch is OFF.
- The engine is stopped.

Condition for Setting the DTC
- The ECM detects that the ECM main relay has been ON (high voltage) for 9-14 second since the ignition switch was turned OFF.

Action Taken When the DTC Sets
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.

Condition for Clearing the DTC
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- Clear the DTC with a scan tool.

Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- Faulty or sticking ECM main relay.
- Misrouted harness.
- Rubbed through wire insulation.
- A sticking main relay may set this DTC.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "DTC P0686" display on the scan tool while moving connectors and wiring harness. A change in the display will indicate the location of the fault.

Test Description
The numbers below refers to the step number on the diagnostic table.
2. If this DTC is present condition, scan tool can communicate to the ECM with the ignition OFF.

DTC P0686

Schematic Reference: Engine Controls Schematics