oki finally decided to do this swap into my 87 trans am previously a TPI auto car.i got a 95 camaro lt1 and im deciding what harness to get my hands on,i got the motor bolted in the car and everything else i can do but the whole idea of this wiring mess now is making me nervous..ive been reading alot ab it lately and well to put it correctly,i dont know jack sh** ab wiring.im assuming if i go to my local junkyard and grab a harness from a 95 roadmaster it'll work am i right? for those of you that have done these swaps using a factory harness please give me your input on this..was it hard? any big issues i should know about? underhood fuseblock? please help me! 9014Josh

Wiring isnt hard, just extremely tedious. You must get it right or youll have problems that are hard to locate

The roadmaster harness will work, you dont need the roadmaster fuse block unless you are doing a minimalist swap

is the fuse block for the roadmaster tied into the engine harness? also aside of hooking up gauges,in order for it to run all i really need to tie into the dash is the ignition and fuel pump correct?

Essentially connect the org wires to 12v battery, pnk wires to IGN and purple wire to the starter

Theres more to it than that but it should get you started

To do it right you cut down the harness to a pile of pigtails and start over from there

ok that helps...how ab my old ful pump relay and those other 2 relays that mount to the firewall next to the brake booster from the tpi harness? do i need to tie those in for anything?

The caprice/impala harness makes a good choice for the thirdgen swap, mounting the computer in the "battery tray" area on the drivers side, as opposed to where the a/c box is using an F body harness, which there is no room for the pcm there on a thirdgen.

Yes you need to retain everything on the C100, the relays for the fuel pump, fans, and the C207 underdash connector, essentially you need to disassemble both harnesses, tie in everything to the c100, the pcm outputs to the relays, add another fan relay (if you want things to work *properly* ), make all of the proper connections at the C207. Virtually building one harness from the two.

which part is the C207? also is the roadmaster harness the same or similier to the caprice/impala?

Im pretty sure the roadmaster also uses the same harness, the C207 is the connector under the dash, passenger side on your thirdgen, it branches off from the ecm connector.

ok thank you,im very glad i have this site or i wouldnt be doing this...whats the majority of the C207? is my ignition and fuel pump tied into that? im becoming more and more confident as i go!

C207 for the most part is the ALDL test port, injector power, and speedometer.

Dont get too overconfident, for a quality swap harness it takes many hours, lots of soldering, and you can easily cause yourself to have to spend a lot of time tracing down a problem if you make a mistake. This coming from someone who has done quite a few.....

dont mean to sound like an idiot now but ALDL? im just tryna get it running...ill spend all the time making it neat and pretty after

Then you are likely going to just cause yourself a lot of headaches, and possibly damage your car.

gee thanks for the help.

The wiring for the swap, when done properly takes many hours, a lot of splicing, extending, a good knowledge of how things work, half of peoples swaps with extra fuse blocks added in turn out like hackjobs, not to mention are redundant, and unnecessary. Going at doing the wiring with a mentality of, i dont care if it looks good, or everything works, will just result in you damaging something, and or causing yourself a wiring nightmare.

You can lead a horse to water...


Your comments show you arent too willing to drink.

It seems like he needs ALOT more research before beginning anything

This is the beginning of a LS1 swap harness

wow that will keep you busy..im looking into getting a harness made from LT1wiringharness.com anyone had one made from them? he says he will do it fir under 500 and seems pretty simple from there

For that price, get a new one

You can make a LT1 harness from a TPI harness. Just add an opti and two 4 wire flat HO2 connectors. 4L60E trans connector if going that route. Everything can be had for pennies on the dollar from a JY, but you will have to completely rework the harness

Ive done more than one harness and have become pretty good at it. It still takes about 4 afternoons

just try and find a impala /caprice harness. If I were you I would use the underhood fuse block that is attached to it. It will make your life easier. try going to lt1swap.com. Good info on wiring diagrams.

ok good thanks..the only reason i saw ill prob get a roadmaster harness is because my local junkyard has about 4 of them i can snag for 50 bucks ea

I started with a Cadillac wiring harness and after a month of screwing with it I went to an Accel DFI system, this allowed me to totally replace all the wires with brand new stuff, plus I got a wideband 02, and software that lets me do what I want. It also has the controls for 2 fan stages, 2 nitrous stages, 700R4 overdrive (knock sensors are extra).

i may end up just purchasing one from LT1350.com but i may wait til the spring now that the cold brutal new england winter is settling in

I don't get around here often, I'm driving my car instead.

Z28ricer built my harness for me, helped me through the install and knows his stuff.

You won't go wrong taking his advice.