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 a battery life. If the PCM relay stops switching and working as it should, the vehicle will not function properly.
What are the symptoms of a bad PCM relay?
The failed PCM relay will turn off the dashboard lights and other key safety warning lights that are normally illuminated when you turn the key in the ignition. Furthermore, and more importantly, the vehicle will usually be unable to start, and it might be impossible to turn the key.
What is PCM relay?
The PCM relay, also known as the powertrain control module relay, comes with a power relay that provides battery voltage to the right PCM circuits. This relay applies to all vehicles that use the OBD-II system, especially those vehicles that are newer than 1996 to present.
What is a PCM and what does it do?
The powertrain control module, aka PCM, is your vehicle's brain. It manages the engine, transmission and other systems based on information it receives from various sensors around the vehicle.
Related Question what is a pcm relay
How do you check a PCM relay?
The only tool required to check a relay is a multimeter. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located).
Where is the PCM relay located?
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.
How do you test a PCM relay?
Where is the PCM on a car?
So your PCM location depends on your car model and manufacturer. But in many vehicles, it is usually found in the engine bay. If it's not there, it might be in your passenger's cavity or under the passenger's side dashboard covered by plastics.
Will fuel pump work if relay is bad?
If the fuel pump relay fails, it will cut off power to the fuel pump, which will render it inoperable, and therefore silent when the ignition is on. While the fuel pump relay is a very simple component, it plays a very important role in the proper operation of the vehicle.
What does PCM fuse mean?
A power-train control module, abbreviated PCM, is an automotive component, a control unit, used on motor vehicles. It is generally a combined controller consisting of the engine control unit (ECU) and the transmission control unit (TCU).