burntorange

the icm went bad so I borrowed a gm spare that a friend had car runs but hard to start at times so I buy a new bwd, put it on car ran for 20 seconds and died, so put the broken gm spare on it and it ran, so I go get one from different parts store and same results any ideas?

John95z28

Did you use heat transfer compound? You need to do that, available off the shelf at some computer stores like staples.

The icm does get hot pretty quick

burntorange

yes sir sure did

John95z28

Okay good. Just for the history, did you have the icm tested and it was bad?
They can be false positive for bad, but your story seems to confirm it.

Obviously you've checked the terminals for corrosion and the wiring for splits etc. How about your ground strap running from the coil? This can potentially be an issue, and it is really cheap to replace.

Shoe has the icm wiring here. Not sure what year you have though or if they are different between years:

burntorange

Mine is a 97, have had both aftermarket ones tested and they test bad, don't understand why the broken gm runs the car tho

Injuneer

Scan if for codes and make sure it's the ICM shutting down.

rngilliland

I wouldn't trust the ICM tests at auto parts stores. Every LT1 ICM I have had tested, at several different brand parts places, showed that it was bad. They all ended up being good and the problem was something else.

What do you mean when you say the GM ICM is broken? If you mean it tested bad but the car runs, then the ICM is probably good.

I would check for a loose connector or bad wiring at the ICM.

burntorange

It's broke around terminals