Hi, when doing the thermo fan conversion with a EL ecu is it necessary to use the original relays and harness or can you use aftermarket relays. I tried using the wires from the ecu to switch aftermarket relays with no sucess.I know the fans both work if i put power straight to the fans.Thanks in advance for any help. PS car is an XG

ECU has negative trigger, Not positive.

Yes you can use aftermarket relays, but the ford ones have diodes to stop any feedback going into the ecu / and or locking the relays on.

Thanks, i"ll chase up a ford harness with relays and try again.