View Full Version : what wiring harness to use?


shoeboxvette
08-30-2010, 02:45 PM
Looking for a harness for my ls1 conversion on my 56 delivery, I have a 99 ls1 out of a vette w/61k miles. Tow company fubared the pcm.tac module and pcm, it's somewhere on the freeway, Soo many choices and price ranges where did you get yours.

46Coupe
08-30-2010, 03:53 PM
Im using a truck harness that I redid and lengthened on mine so I can put the PCM in the interior of my '46. I'd recommend getting a car harness because lengthening was a pain in the ass. Not to mention that I had to change all the injector plugs to go to a car style intake.

If money is no object, there are piles of aftermarket harnesses to choose from. Do a few searches here.

If you choose to do your own, check out LT1swap.com for wiring information as well as a $20 subscription to alldatadiy.com for all the GM schematics.

As for a computer, you can usually pick one up from the forums pretty cheap.

Decide if you want Drive-by-wire or cable throttle body and transmission type before you start buying things.

*edit* Pocket will perhaps post a few suggestions as well, he is regarded as a knowledgeable member here with a great deal of wiring swaps (at least in my mind).

FastKat
08-30-2010, 04:04 PM
Agreed, all that lengthening and shortening was a pain. I would try to get a car harness that matches your accessories, trans, injectors, and DBW setup (if you're going DBW). You might pay an extra $200 or so, but it will be well worth it. If this is your first one, you'll probably have a lot of time in converting the truck harness to fit a car engine.

Im using a truck harness that I redid and lengthened on mine so I can put the PCM in the interior of my '46. I'd recommend getting a car harness because lengthening was a pain in the ass. Not to mention that I had to change all the injector plugs to go to a car style intake.

Marky522
08-30-2010, 06:14 PM
I purposly went with a truck harness as it was cheaper initially and i knew i was going to completely cut it apart (down to individual circuits) and wanted the length. Swapping the injector connectors was no big deal. If you want DBW but want to save some money, if you search the forums someone found out you can use a early vette pedal with the truck TAC and TB, much cheaper this way, you just need to swap 2 pins.

Good Luck,

Mark

shoeboxvette
08-31-2010, 02:39 AM
Thanks for the help,
I've got the harness,just a little messed up at the pcm, need to get the red and blue connectors and pins, Will be using the DBW I've picked up a new tac module and 02 pcm, have the pedal out of the vette.
would like to place the pcm in the storage behind the seat is that too far away?

poconojoe
08-31-2010, 06:12 AM
Thanks for the help,
I've got the harness,just a little messed up at the pcm, need to get the red and blue connectors and pins, Will be using the DBW I've picked up a new tac module and 02 pcm, have the pedal out of the vette.
would like to place the pcm in the storage behind the seat is that too far away?

I've seen the harness extended 5 feet with no issues

Pocket
08-31-2010, 09:40 AM
Since the harness is messed up, it really needs to be rebuild wire for wire. When wires are torn rather than cut they tend to break internally and you have to ohm them out as they are used so you dont accidentally put in a shorting wire that looks good on the outside

That being said, go find a FWD 3.8 car with the newer PCM behind the drivers headlight. It uses the same style PCM connectors as the LSx and is very common in JYs. Cut the connectors off with as much length as you can reach (generally around 3 feet). This nets you the missing connectors and PCM terminals for cheap. Id also grab the TPS/IAC connectors if you're considering a DBC setup

Mount the PCM wherever you like, just check the wiring for excessive resistance. Anything 10' and under should be well within the range limits of the stock wiring as several aftermarket companies offer extensions up to that length