Bad PROM or ECM?

Eric Harper · August 27, 2020

I recently came into ownership of a '94 Chevy pickup with a 350 and a rebuilt 700r4 trans from my dad for $200 (scrap price). It doesn't run because my little brother hooked the battery cables up backward and tried to start it.

It's not getting fuel but the pump inside the tank is running, going to check tonight for fuel flow to the throttle body.

It's also not getting spark, but a click sound can be heard from the coil when the key is turned on.

My question is, since my brother hooked up the battery backwards, is the ECM or PROM unit bad?Is there a way to test either? My local scrap yard doesn't have a single ECM laying around their lot so checking it with a used one is out of the question for now. All the other wiring seems to be good, but I've only been poking around at it for an hour or two here and there.

Any help or advice is appreciated! TIA

riverbanks · August 28, 2020

The click is the fuel pump relay,do you have a test light?I would check for power on + side of coil with key on

Eric Harper · August 30, 2020

Yes riverbanks, the coil is getting 12v+ with the key on. Sorry it took so long to reply back, got busy with other things and this truck is sort of a side project.

riverbanks · August 30, 2020

Do you have a service engine soon light, with key on?

Eric Harper · August 30, 2020

It comes on, shuts off for a quick moment then comes right back on, but I took the ignition module from under the distributor cap and got it tested today. It tested bad all the way across the board so I bought a new one. Later today, I’ll put the new one in and see if that fixes it.

riverbanks · August 30, 2020

Try the paper clip from a to b,see if it will at least give a code 12

Eric Harper · August 31, 2020

As it turns out, the ICM was the culprit of the no spark no fuel. I took it to my local parts store and had it tested, and it was completely fried. After I replaced it, it started right up and purred like a kitten. Thanks for all your help riverbanks!