There are a few ways to fix a faulty ECM/PCM Power relay. The first is to change the PCM entirely. You could also choose to change the relay fuses and change the battery cables as they may be bad already from trying to manage it. Sometimes, it could be that the power wiring in the electronic control or power wiring.

How do you troubleshoot a bad PCM?

  • Locate your vehicle's PCM.
  • Look specifically at the wiring harness.
  • Locate your vehicle's diagnostic data port.
  • Connect your OBD-II scanner to the diagnostic data port.
  • Push your key into the vehicle's ignition cylinder.
  • Watch the OBD-II device's read-out screen for the codes.
  • How do I know if my PCM is bad or ECM?

  • Check Engine Light Turns On. An illuminated Check Engine Light is one possible symptom of a problem with the ECM.
  • Engine Stalling or Misfiring.
  • Engine Performance Issues.
  • Car Not Starting.
  • Poor Fuel Economy.
  • What causes lost communication with ECM PCM?

    The installation of computer chips or performance enhancing devices may not be compatible with ECM or CAN bus wiring, resulting in loss of the communication code. A bent or extended contact lug in one of the connectors, or poor grounding of the computer will trigger this code.

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