P0686

DTC P0686

Circuit Description

The ignition 1 relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit, called an output driver module (ODM). One ODM output control is configured to operate as a low side driver for the ignition 1 relay. The low side driver for the ignition 1 relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the ODM low side driver to turn OFF, the expected voltage on the relay coil control circuit should be a high voltage condition. DTC P0686 indicates an open, high resistance, or a short to ground in the ignition 1 relay coil control circuit. If the fault detection circuit measures a low voltage condition, DTC P0686 will set.

Conditions for Running the DTC

^ The battery voltage is between 9-16 volts.
^ The ignition switch is turned ON.

Conditions for Setting the DTC

^ The ECM detects a lower than expected voltage on the relay coil control circuit.
^ The condition is present for more than 200 milliseconds.

Action Taken When the DTC Sets

^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The malfunction indicator lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC

^ A current DTC Last Test Failed clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Clear the DTC with a scan tool.

Diagnostic Aids

^ The ignition 1 relay will remain powered up for 15 seconds after the ignition switch is turned OFF.
^ This DTC diagnostic table assumes that the vehicle battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.
^ The following underhood fuse block terminal locations correspond to the ignition 1 relay circuits:

- F13--Ignition 1 voltage circuit
- F14--Ignition 1 relay coil control circuit
- H13--Battery positive voltage circuit to the ignition 1 relay coil
- H14--Battery positive voltage circuit to the ignition 1 relay armature

Test Description

3. The engine will crank and run, with a short to ground on the ignition 1 relay coil control circuit. This condition could result in a discharged battery.
5. The engine will crank but will not run, with a high resistance or an open on the ignition 1 relay coil control circuit.