I have now traced the wire that renders my fuel pump powerless. The wire runs from the ECU to the fuel pump relay. It must carry a - charge in order to work the pump. But unfortunately, it is not giving out power so I am suspecting the ECU to be the culprit. I do not know how I can resolve this problem? Can the ECU be repaired?

  • Have you reviewed the details of this posting?. In fact this seems a duplicate of that, kinda, sorta. Oops. That's you. Are you sure about the CPU signal to fuel pump PWM driver? If no module perhaps the PWM module is inside the ECU. In that case you need an oscilloscope to see the signal.
    – zipzit
    Commented May 30, 2017 at 19:48
  • Whats up, its you again. I am very grateful for your concern. A Ground wire to fuel pump relay is the problem. I checked and no ground wire is coming out. I try other source of Ground and the pump would work. I am afraid since this wire comes from the ECU it could also be carrying other signals to the pump. My major problem now is that the car is consuming to much gasoline. Here in Liberia, West Africa I just trying to run it as a taxi to survive. So any other advice? Commented May 30, 2017 at 22:24

2 Answers 2


ECUs are not easily repaired. You may wish to replace it with one from the junkyard. This will also confirm your diagnosis without the cost of a brand new ECU.

Also, on cars this age, make sure to test the entire electrical circuit. Your little wire may not giving the power it is supposed to because of:

  • bad connections
  • bad relay
  • bad fuse
  • bad ground
  • corrosion

ECUs can be sent off for testing and repair. Here in the UK testing is usually £30-50 and repair is around £200. Search for ECU testing and repair in your area.

Although if you are good at electronics / soldering and are sure the ECU is at fault you can open the ECU and follow the PCB trace to work out what components control the relay, usually a fault like this is caused by a faulty Mosfet which is a 3 pin device.

If you purchase a second hand ECU it may need to be programmed, some will require physically swapping a chip, some may just need the keys programming.

There is also a possibly that the ECU is not at fault. Are you sure the ECU is meant to supply a live? Most ECUs switch the Ground of relays and the Live would be supplied from the fuse box.

There could also be a fault that the ECU is being told not to switch the pump on, for example an immobiliser fault, or a missing live or ground to the ECU. In this case a code read and then checking each wire against a pinout would rule this out.

  • Thanks guys for the concerns. The wire from the ECU is actually a Ground. You are correct. What happen is that this particular wire is not delivering the Ground to the relay for the pump to work. So I am planning to just attach a Ground wire to see if it works properly. The car consuming more fuel. Here in Liberia I running it as a Taxi. It use to consume quite less gasoline but since this power lost to the pump I decided to attach to pump wire to other sources it has been consuming more gasoline. Commented May 30, 2017 at 22:16

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .