guys i really need your guys help here. Im currently swapping my 1989 5.7 into a Ls3. Im trying to remove old harness as im replacing it with a holley termionator max control system. It will completely control engine and has all sensors plugs, injectors, fuel pump relay and even 2 outputs to control fans. HOWEVER im stuck on what to keep and what to trahsh on my harness. With the research that ive done, I understand the harness on the passangers side is complete engine control? and I have a harness on drivers side near brake booster for necessity items like headlights, i believe its called the c-100 ? ANY HELP/GUIDANCE IS MUCH APPRECIATED, wiring diagrams ECT ECT

 

Take a look at the stickies and read up on LS harness prep. If you are keeping the stock gages you will need to retain many of the circuits coming from the C100. The C100 has both a headlight harness and engine harness. The main engine harness goes through the passenger side fender well but all communication and fuse block power is routed through the C100.

google austin 3rd gen for wiring diagrams but take some time to read the stickies. All of your answers are in there.

https://www.thirdgen.org/forums/ltx-...p-3rd-gen.html

 

Soon to be doing the same thing only I will be using a carb setup ontop of the LS
I was reading through some of the sticky's and they don't have much info on making gauges work with a carb

 

Why do people keep thinking gauges are some mystery? It's no different than any other engine. Oil, water temp and tach are the only ones from the engine. Tach will come from the Holley/MSD spark control box oil and water temp are covered in the swap gauge. Speed is covered elsewhere in this message board, a simple search will show you your options

 

It's not that it's a mystery, I just haven't done it before.

What do you mean "the swap gauge" ?
Is this a swap you have done yourself?

 

Swap guide
Yes, several LS swap in several different vehicles and I build my own harnesses. It's easy if you actually do ANY research, especially when almost any answer you could think of has already been answered AD NAUSEAM on this site and the rest of the internet. If you look to see when I joined here and sech my posts, almost all are answering other questions because I read, then I read some more, then I read more later, then I got to sleep and wake up and read again. I learned how to make my own harnesses by reading and researching, then researching some more.
As much as I despise government indoctrination centers I now understand the importance of HOMEWORK. Those who read and research are more likely to succeed.

 

I have some tips and tricks hot linked in Post #1 of my build thread.

https://www.thirdgen.org/forums/ltx-...-qwktrips.html

Your factory oil pressure gauge can be operated from a LS1 Camaro oil pressure sender (1 wire). The resistance range isn't entirely matched to your stock gauge but it's close enough for government work. It's further off if you have a v6 gauge.

You'll need to use the LS3 oil pressure sender (3 wire) if you want oil pressure data logged in your Holley EFI. Unfortunately it cannot drive your factory gauge. Since you have a carbed intake you will have plenty of room to put a tee off the engine block and mount both senders.

 

As far as what to keep and what to trash, I followed every last wire back to where it came from and if it wasn't needed then I removed it. Unfortunately I did not have the luxury of a schematic at that time. If I was unsure at all then I left the wire in place. It's kind of like a puzzle, the answers you didn't know earlier become apparent towards the end.

 

dude easy its my first ls swap ......kickback bro .....im a college graduate IBEW member just looking for somw help

 

I think there's been some good advise so far in this thread. Here are some items I've found helpful as well. All of this applies to wiring, but some of it is more general for LS swaps:

• Search. Research. Read lots of build threads. Take notes and make plans. Ask questions when you run dry.
• Not every year of thirdgen is the same when it comes to wiring (there are differences also between engine/tranny combinations and between camaro/firebird in the same year). The best way to go about this it to research and the find the wiring diagram(s) that match your specific vehicle and then verify that they're right by comparing the wire colors and where they're supposed to be between diagram and car.
• If you can find it / afford it, find a Helms manual for your year / make car. I found mine on ebay a long time ago. It has the best wiring diagrams and has all of the combinations for your year / make. Then you just have to figure out which one(s) apply.
• Don't just cut wires if you can disconnect them from source or destination. If you're going to have to cut a wire, think hard about how much of that wire you will need for when you solder something back to it.
• Don't throw away any wiring. You're going to question what you did later or need some wire to patch something back together. It's really nice to have good quality wiring with colors and gauges to match what you need handy.
• Start taking notes every time you work on the car, as you won't be able to remember all of the conclusions you come to. If you wire something up, diagram it out and keep it somewhere safe for when you need it again. Otherwise all you have are guesses on memories when it comes time to diagnose an electrical issue (which will happen, it's only a matter of time).
• There are inexpensive ways to go about doing this and there are nicer, but more expensive ways. There are also nicer ways that just take more time or effort. When you get in a hurry, you're likely to pick hackjob ways and regret it later (or maybe you won't! Everyone is different).

On my car - passenger side harness was engine control, C100 harness had power and some sensor wires and a second piece of C100 for headlights, then there was a harness underneath the brake booster for cruise control. I started by removing the passenger side harness all the way back to the passenger compartment and labeled what was i the cabin that hooked to the ECU. The headlight half of C100 I left alone. The other half, I identified each wire using a Helms manual and tracing, labeled them, and then cut leaving as much slack as I could. I recently removed the cruise control harness after tracing everything back into the passenger compartment and ensuring I knew what was still needed and not.

The first round of my swap, I used a Speartech harness and trusted the instructions and just hooked stuff up accordingly. It worked. I only ran it a few hundred miles (at the most) before wanting to do more with the swap. Having reviewed my own work from that long ago, if you choose to go this route I'd recommend you source fresh power whenever needed and not tie into anything under the dash for BAT/IGN power. There's more you can do to make this better, but this is the minimum.

Have fun!

 

• Not every year of thirdgen is the same when it comes to wiring (there are differences also between engine/tranny combinations and between camaro/firebird in the same year). The best way to go about this it to research and the find the wiring diagram(s) that match your specific vehicle and then verify that they're right by comparing the wire colors and where they're supposed to be between diagram and car.
• If you can find it / afford it, find a Helms manual for your year / make car. I found mine on ebay a long time ago. It has the best wiring diagrams and has all of the combinations for your year / make. Then you just have to figure out which one(s) apply.

This is 100% factual information, and I second that as a GM Engineer.