ECMB Fuse Blows

Posted in Crank, Oil and Piston
  • I have been trying to figure out why I keep blowing the ECMB fuse on my sons 1990 G20 van. It blows as soon as it is replaced. I checked all visible wires for shorts. One of the injector wires was flattened by the air cleaner. But Insulation was not broken. I can’t find anything else. Do I need to check all wires under the wire looms? I replaced the fuel pump, fuel filter and fuel pump relay. The fuel pump does run when the key is on. I tried pulling the connectors off of the fuel pump relay and the oil pressure switch. Still blows. Pulled connectors off of other sensors. Still blows. Removed the connectors from the computer. Fuse doesn’t blow. The computer was just laying along side the drivers seat. Could it be a bad computer blowing the ECMB fuse? Or is it just a problem within the fuel pump circuit? I disconnected the harness leading to the fuel pump. The connector is underneath the van coming out of the engine compartment. So that eliminates any short from there to the fuel pump.

    There are One Answer for "ECMB Fuse Blows"

    1. hangtrojanover says:

      The best thing to do is to get a wiring diagram that shows every place that this fuse supplies power to. Just because it says what it’s for on the fuse does not limit where power can be distributed to after the fuse. A lot of these kinds of fuses fed some of the emissions solenoids for the motor. I am not sure of this, but do know GM does this quite a bit. Go to the dealer and the service department and ask for a wiring diagram of what you are dealing with.