Thread: 2003 transmission

Well, I bought a 2000 GTP with a blown trans. I found a low miles XAB transmission to put in it. Little did I realize until I had it in that the 2003 transmission is different from the 98-02.

So, I do more research (after the fact) & find a thread about rewiring the plug on another forum that supposedly others have had success with. Did that and the car is driveable. It has all gears but line pressure is low in first for sure. Under light throttle it will slip and catch a little and no way would I try a full throttle start. Obviously, I don't want to damage the trans and want to figure out how to fix it right.

So, my understanding is there is something special about the 2003 computer and I should be able to swap one of those in, wire it back the way it was and it will work. Problem is, coming up with a computer from a 2003 GTP (for correct gear ratio & s/c). If I do a search on car-part a jillion other vehicles come up as a match. Morad is an option but says their reflashed pcm won't work with HPT which I'd like to do in the future.

Any suggestions?

Blue, yes that was my first idea but I have a hard time believing the work involved to chase down the right computer will be harder than replacing the tranny again. Once I have the right 2003 computer I think everything will be fine. Next on the hunt are wiring diagrams for the 2000 & 2003 cars to figure out if there are any other differences that could throw a wrench in the works. Not to mention I hate to get rid of a tranny w/ under 20k on it.

Thanks Mech. I hadn't thought about searching eBay for the computer. I'll see what I can find about researching those numbers.

Originally Posted by bluegtp91

Sell that '03 transmission and get a '97-'02 trans.

Blue, please tell me that was a typo. I can't believe anyone would recommend a 97 tranny.

I did a 05 impala ss drive train swap in my car maybe 6 months ago, I too didn't know any problems would occur. I was at maximum line pressure and was throwing the 1810 code. I was lucky and found a 03 gtp pcm and it has worked perfect ever since. The service numbers don't matter, but what matters is it must be a 03 pcm from either a gtp, or gt whichever you have. I didn't even have security issues like I thought I would. The only problem was my emission test, it came up as vin mis match and was kind of a hassle.