ECM Installation

I have a 1991 Grand Prix 3.1L V6 that I suspect the ECM needs to be replaced in. I have a good used ECM that I would like to swap in. Is there anything special that needs to be done or can I simply unplug the old one and plug in the new one?

Thanks!

I have a 1991 Grand Prix 3.1L V6 that I suspect the ECM needs to be replaced in. I have a good used ECM that I would like to swap in. Is there anything special that needs to be done or can I simply unplug the old one and plug in the new one?

Thanks!
Welcome to AF, unless it is the exact same ecm for that car, you need to swap proms, other than that and the usual idle relearn issue, do it.

To add to Max's suggestion, make sure the GM service numbers match on both units. And for clarification, even if the service numbers match, you still need to swap the proms as he said, as one ECM service number can be used with several different combinations, and the PROM is calibrated for your car.

Thanks! Do you mean that the prom is unique to the specific make, model, engine size etc. or unique to each car? Also, is the prom simply plugged into the ECM?

Thanks! Do you mean that the prom is unique to the specific make, model, engine size etc. or unique to each car? Also, is the prom simply plugged into the ECM?

Here are pics of an ECM module from a '95 Grand Prix with 3.1L.

http://i5.photobucket.com/albums/y186/lizzywiz/ecm95.jpg
Service Data Label where the SERV. NO. numbers must match. ECM programming is unigue to a specific year, make, model and engine size.


http://i5.photobucket.com/albums/y186/lizzywiz/ecm95_2.jpg
Arrow points to the location of the PROM. Remove the cover. For safety so you do not damage the chip with electrostatic discharge make sure you wear a wrist band grounding strap clipped to a good ground. You can use a chip puller or however method you feel comfortable with.

There is a little cover on the ECM held in by two screws. The PROM is under that cover. It is held in by two plastic clips that are released by pushing them outward and down.

Sorry, Bob, were answering at the same time, and it took a bit between customers for me to complete my reply.

There is a little cover on the ECM held in by two screws. The PROM is under that cover. It is held in by two plastic clips that are released by pushing them outward and down.

Sorry, Bob, were answering at the same time, and it took a bit between customers for me to complete my reply.

No problem Rich. I thought you were calling it quits for the day. Didn't want to see him left in limbo. Plus I had these pics in my collection.

Thanks alot guys! And Thanks for the pics too. I was able to get the prom out no problem. Now I just have to wait for the other ECM to get here since I don't have it in hand yet.