Hello everybody! Thanks for having me here.

I just acquired a complete '03 Bonneville NA engine with a '97 Grand Prix GT wiring harness and PCM. My understanding so far is that I already have a bastard of a parts collection. However, I am wondering how much different a '97 GP GT and '03 Pon Bon SSE are mechanically. Considering that this setup will be for an non-GM swap and any harness will need to be modified, is this going to work for me?

From what I've heard, the '97 just has different MAF tables, injector clips, and an inferior transmission. If that's the case, I don't care because all of these parts will be changed out anyway. (bigger MAF, bigger injectors, manual trans) As for the '03 engine, I've heard that these are a little different from the -'02 S2 engines, but haven't figured out why.

Can you guys help a newbie out? If I need to get a different harness and PCM it's no biggie because I bought this for $20. I just don't want to fry anything or chase down tricky issues that could easily be avoided ahead of time. Thanks!

If anybody has wiring diagrams for an '03 that would be helpful as well. Thanks!

Maybe I'm posting in the wrong spot? Anyway, I've solved the issues with a little help from some well written Fiero articles. Although labor intensive, I was easily able to convert my '97 harness to work with a '98+ ECM. There are a couple charts out there with the pinouts of both ECMs so you can just swap all the wires accordingly. If anybody is interested in how it's done, let me know.

What is your long term goal? What car is this going in? What year trans? The h-body and w-body engine harnesses are very different. The bulkhead connectors are not the same. Pretty much scrap the harness and PCM you have and find something better suited.

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Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler