P0685 CHEVROLET code

The voltage in the relay coil control circuit is normally low. If you see trouble code P0685, it means that the PCM’s fault detection circuit has detected voltage from the relay that measures above the normal parameters – above 4.6 volts with the key turned on.

What is ECM PCM power relay control circuit open?

The diagnostic trouble code (DTC) P0685 stands for “ECM/PCM Power Relay Control Circuit Open.” The powertrain relay typically stays in the open position, and battery voltage constantly goes to the relay. In the ECM/PCM, an output driver module (ODM) acts as the ground path for the relay coil control circuit.

Where is the ECM power relay?

engine main fuse relay control box

The relay is located in the engine main fuse relay control box. The defective ECM-power relay is removed from the control box by pulling it straight up and out of socket. The new ECM-power relay is installed into the socket and the engine scanned for codes.

What does a PCM power relay control?

The ECM power relay, or the PCM relay, acts as a switch that provides power to the ECM. when the ignition key is turned off, the switches within the PCM relay no longer receive battery. If the PCM relay stops switching and working like it should, the vehicle will not be able to function properly.

How do I get rid of code P0690?

What repairs can fix the P0690 code?

  1. Replacing the ECM/PCM relay.
  2. Repairing ECM/PCM power wiring.
  3. Replacing ECM/PCM fuses.
  4. Replacing damaged battery cables.
  5. Replacing the ECM/PCM.

How do I fix code P0685?

What repairs can fix the P0685 code?

  1. Repair of shorts or bad terminals or connections.
  2. Replacement of the powertrain control module relay.
  3. Underhood junction block replacement (fuse box)
  4. Replacement of battery cables and/or connectors.
  5. Fuse replacement.

How do I reset my ECM?

Zitat von Youtube: Position to disconnect the positive battery cable. 3 wait 30 seconds for tap the positive terminal cable to the positive battery post. 3 times 5 reconnect the terminal cable 6 start the vehicle.

What are the symptoms of a bad PCM relay?

7 Common PCM Failure Symptoms

  • Your ‘Check Engine’ Light is On. …
  • Your Car Won’t Start or Starts Roughly. …
  • Sudden Loss of Gas Mileage. …
  • You Failed Your Emissions Test. …
  • Your Engine Stutters or Stalls. …
  • Erratic or Random Shifting. …
  • You’re Receiving a PCM-Related Error Code. …
  • What to Do If You Experience PCM Failure Symptoms.

How do I know if I need to replace my PCM?

What Are the Symptoms of a Faulty PCM?

  1. Your “check engine” light is on.
  2. Other warning lights may be on, including traction control and ABS.
  3. You lose fuel economy for no apparent reason.
  4. Your car stutters when starting, requires multiple attempts, or won’t start at all.
  5. Stuttering or stalling during idling.