I just swapped in a 3100 out of a 1994 grand am se.. now im stuck... I used the engine harness out of the grand am.. it looked like it was hacked up... starter has like 6 wires coming off it for contstant power to what? idk... I got power to the pcm... but nothing works.. no spark injectors.. or that good stuff... i think i need to hook up some wire/s to the ignition but cant really find what i need to do... have searched many sites, wiring diagrams.. and i just dont understand what needs to be done..

Do you have the wiring diagrams for both your car and the donor car? You really need these to successfully do a wiring job. I'll tell you that I used the starter wires, relay, and battery wires from the J-body. I carefully removed them from the factory harness before cutting the rest from the C100 connector, then carefully spliced what needed to be spliced from the V6 harness.

I have the diagrams off of autozones website... they seem a little harder to read then some other diagrams i have seen.. I used the factory wiring for everything in the car... havent cut a single wire out of it YET... i think its because there is soo much to do with the wiring i just get overwhelmed and start to get confused.. guess ill just poke at it for a few days

What I would do is to take the loom and wrap off of your factory harness, and separate out the following:

ABS wires (the twisted pairs that run to your front wheels)
Starter wires (should be a thick purple wire going to a relay, then to the starter)
Battery wires to the starter and fuse box
All wires going from the C100 connector to the fuse box
Neutral switch plug on the tranny
Cruise control, if you have it

Basicly, anything that runs to the C100 or fuse box, but has nothing to do with the ECM, keep it. If you end up with a duplicate later, you can always remove it.

After you've separated those out, I would start tracing and labeling all of the rest, then cutting them, with plenty of length.

Once you have done all of the above, you need to pull the loom and *most* of the wrap from your V6 harness.

then you need to trace the wires that need to go from that to the fuse box and C100 connector, and label them. There should be a firewall plug on the GA harness, so that's where you're looking to cut them. Basicly anything that goes from the ECM or engine to the firewall plug needs to be cut and spliced into the J-body C100 connector. You're going to want to double and triple check these and make sure they are absolutely labelled correctly before you cut them.

Once you have that done, get the harness on the engine, and try to run it where it will be sitting, then start laying the wires from your car into it and putting electrical tape around the harness to hold it together. Match up the wires from the harness and the wires from your car, and tie them or tape them together so you know what goes to what. Eventually, you should have all wires pretty much where they go, and the entire thing bound together. You can then take it off the car and bring it to a bench to commence the splicing. Take your time and properly twist, solder, and shrinkwrap the splices, then put it in place and try it out. If all goes well, wrap it and replace the loom.

This is how I built my second harness. The first one, because it came from a RWD car, I pretty much just shredded, and ran each individual wire from each plug on the engine back to the ECM and C100, because I had to change everything around. The way I described to you is the easiest, because it allows you to properly fit every wire where it goes, and then take it to your bench for finishing.

Hope this helps.

Great help.... That will get me plenty farther then where I am currently... Where is the C100 connector? either i dont read enough (or dont remember)... i have read all the topics on v6 swaps at least 3 or 4 times before i actually started the swap..

C100 is under the aircleaner /power brake booster area

alright.. so its that big plug up by the master cylinder area... got it.. tomorrow i will pull the harness back off the engine... I tried to start it today but PCM didnt want to play...