Pontiac Repair: ignition control module, mopar ford, pontiac grand prix

Question
I have a 1997 Pontiac Grand Prix 3.8L Supercharged and I went to change the ICM because the old one is bad. Changed the ICM and the car wouldn't start. Put the old one back on and car started right up. Why?????? I have heard the new one needs "flashed" but why? It's not a PCM, just a ICM.

Answer
Hi Gary:

No an ignition control module is just plug and play no flashing needed. What is wrong with the old one that your replacing it with a new one that doesn't work? My guess is that the new one is either bad out of the box or it's the wrong one for the application. A "fits all" is not the way to go. Especially aftermarket. I'm a firm beliver that you put back on the car what it came with from the factory. Not just Gm but Mopar,ford,Toyota etc... when you go aftermarket your just asking for problems. for your car you want an ac Delcom genuine gm replacement part.
Good luck :)