EcCM 1 fuse

TEXASJ85

MEMBER
1991 GMC SONOMA
2.4L
6 CYL
2WD
MANUAL
184,033 MILES

I am trying to find out what the ECM 1 fuse powers. Keeps blowing the fuse when turn ignition switch on. We changed the pump, filter, checked wires for shorts, checked ground wires. Everything is okay and bypassed the ECM from battery straight to the fuel pump and it works, but truck still does not start and still blows fuses. Thank you

2 Replies

CARADIODOC

MECHANIC
33,752 POSTS

A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a twelve volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it is not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.