Ok, so I've been dormant for a while here, got married, moved, yada yada Yoda... long story short, my wife and I are finally going to finish our 92 project car. I'll be picking up our donor car this Tuesday as I'm told that for a swap, the whole car is the only way to go. Now,, all the mechanics of the swap I am familiar with, I'm very mechanically inclined, however the wiring is freaking me out. I know very little of automotive wiring, that being said, all the writups about swap harnesses might as well be written in hieroglyphs... my questions are as follows,

Where does the third gen harness meet fourth gen harness? Or are they made one in the same? Ie dashboard harness/engine harness

I noticed that the 01 donor z28 has a vats key... does this help me at all?

Does the entire third gen harness need to be removed? Or just the engine harness at the firewall?

I just can't find any info that makes sense to me.. everybody does it a different way, I would like all my factory gauges to work, and everything to function as it should.. just with a different beast under the hood.

I apologize in advance for my electrical illiteracy

 

I'm assuming your doing an ls swap into your car. Someone will come along with a more detailed answer but for now the computer under the dash on the ps can be unplugged and pulled into the engine bay. I believe starting in 88 or so that the harness for the gauges and engine are all In one. You could either spend the time to separate out the wires you need for the gauges or get a body harness from an 87 or 86 firebird, they would have the separate engine harness and a plug for the electric speedometer those two years. As for the vats, you can have your ecu re flashed to remove it or use the module and key form the donor car. And to answer another question the entire engine bay wiring can be removed without touching the interior wiring. On the ds there is a 1/4 bolt in between the headlight harness and gauge harness. Unbolt it, the bolt probably will not come completely out, and the engine bay wiring is now separate from the dash/interior wiring once unplugged.

 

To clarify, yes it is an ls1 that I am swapping.

I have read a fee places about a 3 wire/ 5wire hookup. Something like starter/alt/and a few other things, no one ever really specifies all the rest....?

Aside from getting the engine to start and run.. from what I've read that doesn't seem to be the hard part.. accessories Like gauges and such are what's confusing me. Everybody seems to stop the writeup before they get to that part.

 

And of course the more research I do, the more confused I get.. I went to books a million today and bought a book on wiring ls engine swaps and it only buried me more.. I'm so lost

 

Just got the car today, a blue 2001 z28 with a little front end damage. The frame is not repairable, and that's just the way I wanted it. I was really trying no to take a good car off the road. The muscle car breed is already endangered enough.

On a side note, I have continued to try and gather as much info on the wiring as I can, and for now, I have figured out how to build a stand alone harness. My next goal is to figure out how to make my factory gauges work.

As of now (not that anyone cares) this has tuned into my official swap thread.

 

Moved this to the LTX and LSX subforum.

I tried reading up and studying diagrams before starting the wiring work, and found it didn't make any sense until I actually started doing it.

Using the 4th gen fuse/relay box made it easier for me. It will have a bunch of circuits you won't be using, but you'll also have all the circuits you do need.

The gauges shouldn't be that hard. The tach is easiest (in my opinion) by switching the tach output in the PCM from "6" to "3", which will make the pulse output match the '92 V8 tach (assuming you have a V8 car - if it's V6, then set it to "4"). I didn't do it personally, but I understand the oil pressure output from the PCM will work directly with the '92 gauge. Speedometer - again, use the PCM output to the '92 speedo input - you may have to do other PCM setting changes to get the speedo to read correctly. Voltage gauge isn't affected. Temp gauge can be a little tricky, but a '97 CTS with 3-pins can use two to the PCM and one to the dash gauge (I believe the resistance is compatible between the two) - an adapter harness that has the 3 pins to the CTS with a 2-pin connector to the PCM harness and a pigtail for the gauge is helpful.

I did two 3rd gen LS installs without doing much of anything with the PCM harness. My 3rd LS swap was into a '57 Chevy, and I jumped in with both feet on it. Looks intimidating, but bottom line is, in this pic, everything is labeled, and when I went to start the car for the first time, everything worked.

 

You sir, are awesome. My apologies for not posting in the correct forum, I had suspected that the swap forum was the appropriate place. But I really appreciate the support and info.

 

I just want to correct something with the VATS.

You don't have to delete it providing its fine now. Basically in both cars (3rd gen and 4th gen) there is a module that is mated with your specific ignition key. The modules both send a starter enable signal and fuel enable signal.

So basically there are two output wires, and in reality there is only one that you need to deal with. There is a connector that connects the body harness to the ECM, it is C207. One of the pins in C207 is the fuel enable signal, just run that wire to the corresponding location on the new PCM. Its actually much easier than it sounds.

On your ecm i think it is either:

Connecotr 3, pin F10 if you have TPI

Connector 1 Pin B6 if you have TBI

just route that wire to your new ECM, and your done.

 

I was actually not to worried about vats because it appears that both cars have a similar systems, however, the swap-into car is a 92 auto v6 car. It used to be an auto, but I swapped in a t5 a while back, and now I've got the donor car for the swap I have dreamt about for years, but I'm missing a t56, and a swap harness. Can anyone point me towards a pic of the 'c' connectors pin outs? All I should have to do is remove both harnesses at the firewall correct? In other words, nothing from under the dash is swapped?

I have also been reading up on pockets 'ls1 harness start to finish'. His final installed product looks so good, that's what I'm trying to shoot for. Although none of the picks in kids thread show up due to photobucket which makes it a little tougher to understand, but I'm getting there.

I'll be posting pics later...