P0685
DTC P0685CIRCUIT DESCRIPTION
The powertrain 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 powertrain control module (PCM) supplies the ground path to the relay coil control circuit via an internal integrated circuit, called an output driver module (ODM). One of the ODM output circuits is configured to operate as a low side driver for the powertrain relay. The low side driver also incorporates a fault detection circuit, which is continuously monitored by the PCM. When the PCM commands the relay ON, the expected voltage on the relay coil control circuit should be a low voltage condition. If the fault detection circuit measures a high voltage condition, DTC P0685 will set. DTC P0685 indicates a short to battery positive voltage, or ignition 1 voltage on the powertrain relay coil control circuit.
CONDITIONS FOR RUNNING THE DTC
The battery voltage is between 11 - 18 volts for 2 seconds with the ignition ON.
CONDITIONS FOR SETTING THE DTC
- The PCM detects more than 4.6 volts on the relay coil control circuit, with the key ON.
- The PCM sets the code instantly and turns OFF the ODM for PCM protection.
ACTION TAKEN WHEN THE DTC SETS
- The PCM will not illuminate the malfunction indicator lamp (MIL), if this diagnostic runs and fails.
- The engine will crank, but will not run, or the engine will crank and run in reduce power mode.
- The class II communications will be available with the use of a scan tool.
CONDITIONS FOR CLEARING THE MIL/DTC
- A current DTC, last test failed clears when the diagnostic runs and fails.
- A history DTC clears after 40 consecutive warm-up cycles, if no other failures are reported by this, or any other emission related diagnostics.
- Clear the DTC with a scan tool.
The P0685 diagnostic table assumes that the vehicle battery is fully charged.
TEST
Steps 1 - 4:
Steps 5 - 6:
Steps 7 - 9:
Steps 10 - 16:
