Symptoms of P0685 OBD II Trouble Code
- A defective PCM power relay
- A blown fuse or fusible link
- Corroded or damaged wiring or wiring connectors (especially near the PCM relay)
- Faulty ignition switch
- Partially or totally disconnected electrical terminal at the ignition switch
- Loose or corroded battery cable ends
Common Causes of P0685 OBD II Trouble Code
- References to the "ignition switch" in this instance refer to the electrical portion only
- Swapping identical (matching numbers) relays for testing can be very helpful
- Always return relays to their original position, replacing the defective relay with a new relay
- When testing system fuses, make sure that the circuit is at maximum voltage