CSX TIII and wiring

[iTurbo]

It looks like I'm going to spend my vacation building a TIII for my old '87 Shelby CSX.

I'm a little concerned about wiring it up though. If I had my say, I'd just modify the '90 Shadow ES harness I have for TIII use. The owner would rather use a Spirit R/T harness I have as a donor though. I'm sure I can make either option work, but fitment is a concern to me.

I'm sure I could make the '90 Shadow ES (SBEC) harness fit like a glove, but I'm not so sure about fitting a Spirit R/T harness in a P-body. What have other TIII/P-body owners done?

We're going to rip out the original LM/PM harness and install an SBEC based harness for sure. The P-bodies are really different. There is a multitude of connectors (under the dash) rather than a main bulkhead like most other cars.

[jonnyb]

Yup - bulkheads in the p-bodies are a unique animal in that they're not bulkheads at all - they're just a bunch of smaller connectors! The best part is that it seems like every year they made changes to all the little connectors, so you can't even swap from one year p-body to the next without having to rewire under the dash.

Your 90 p-body harness will not plug into the 87 dash/bulkhead, so honestly, I would go with the spirit R/T harness. That way the entire engine side is done for the T3 (spirit and shadow have exact same engine bay so everything fits plug and play) and all you will have to rewire is the connectors under the dash. Oh wait, actually, I just remembered it's an 87 csx - I think the headlights might be different so you may have to swap a few connectors to get that to work, but still easier than changing your p-body harness to work with the T3.

I'm doing this same swap right now, except I'm doing it in a 91 shadow (and I'm going to use the spirit dash and wiring as well because I like to complicate things...LOL).

Jon

[iTurbo]

Yup - bulkheads in the p-bodies are a unique animal in that they're not bulkheads at all - they're just a bunch of smaller connectors! The best part is that it seems like every year they made changes to all the little connectors, so you can't even swap from one year p-body to the next without having to rewire under the dash.

Your 90 p-body harness will not plug into the 87 dash/bulkhead, so honestly, I would go with the spirit R/T harness. That way the entire engine side is done for the T3 (spirit and shadow have exact same engine bay so everything fits plug and play) and all you will have to rewire is the connectors under the dash. Oh wait, actually, I just remembered it's an 87 csx - I think the headlights might be different so you may have to swap a few connectors to get that to work, but still easier than changing your p-body harness to work with the T3.

I'm doing this same swap right now, except I'm doing it in a 91 shadow (and I'm going to use the spirit dash and wiring as well because I like to complicate things...LOL).

Jon

So good to talk with someone that knows exactly what I'm talking about!

P-bodies are so weird compared to the other body styles. It's a bummer that my '90 Shadow ES harness won't work in the '87 CSX. I've talked with the new owner (a local friend) and we've pretty much decided on using a Spirit R/T harness as a base. That would take care of the engine side of the conversion for sure. I am just now completing a Masi 16v harness in my Shelby Lancer, so it can't be that bad.

EDIT: The '87 CSX originally used H6545 headlights. I have a set of Euro H4 headlights ready to go for it. So that will be part of the conversion.

[Pat]

I've done it both ways. I converted a 91 t3 harness to plug into the million p body dash connectors, which was a pain in the ---. I also converted a '90 p body turbo engine harness to run a T3, which I thought was less of a pain in the ---. I'm now swapping the entire body, dash and converted to run a t3 engine harness from said '90 p body into an '88.

No matter how you cut it, converting p body harnesses is a bit of a hassle given the lack of a bulkhead.

[jonnyb]

Agreed - if he was doing the conversion in a 90 shadow, I would say modify the engine harness for the T3 and be done with it, but the fact that he's starting with 87 under dash wiring brings no benefit to using a 90 p-body engine harness because he would have to rewire for the T3 (less of a pain in the @$$) AND rewire to fit the 87 under dash (more of a pain in the @$$). So he'll have the worst of both worlds. LOL!

My last couple of nights have been spent restoring the T3 engine harness I have and starting to create my repin/remapping chart so I can start to make the required changes to fit the p-body. As I mentioned before, I'm actually going to run the spirit dash in the shadow, so I don't have to repin at the bulkhead (will use spirit bulkhead and dash wiring). Instead I have to repin the the right and left rear wiring harness (basically swap Spirit wiring into original shadow connectors) so that the spirit dash harness connects seamlessly and operates all the power windows, locks, mirrors, tailights, etc. It doesn't look that bad, but there are a few feeds that I haven't figured out how to make them work yet.

Good times!

Jon

[Turbo Joe]

what I did was use an 88 shadow es harness that is nearly a plug and play for an 87 except you now have a smec plug you change over to a sbec plug by adding in a spirit r/t under hood harness to the 88 under hood harness and your done.

[jonnyb]

I remember Pat taking pics of some of the 88 connectors and labeling them for me about 10 years ago when I converted my 85 GLH-T over to SMEC using an 88 p-body harness. I looked at them and all the various connectors and though "what did I get myself into?" LOL! However, I think the hardest part of it actually turned out to be me having faith in myself understanding the wiring. I must have gone over and over it a hundred times before I plugged it all in...LOL!

The problem is that he doesn't have an 88 harness, and finding a good one of those these days is pretty darn tough!

I may have an entire 90 interior harness. I know I usually don't keep those when I strip cars, but I think for some reason I kept either a 90 or 91 complete body harness. If the entire car is coming apart (is this complete resto or just T3 conversion?), then it might be easiest to swap in the entire 90 harness and modify the engine side for T3. Of course, that's only if the entire car is coming apart for resto.

Jon

[iTurbo]

Thanks for the feedback guys; it helps immensely. I was really hoping the '90 Shadow ES Turbo harness I have would be a more friendly option, but it doesn't look like it would work out as well as I hoped. I'll keep it on the shelf and use it for a future project though.

I did once convert an '88 Omni TBI harness to Turbo II (think homemade S60 harness) and that worked great and fit the donor car perfectly (the same '88 Omni the harness came out of). Fit like a glove.

Looks like I'll be using one of my Spirit R/T harnesses for this job. I'm sure I'll have to sacrifice the '87 CSX's original harness to make this happen, but oh well. I'm taking vacation soon and am going to use the time to build the TIII for the car. Ported head/manifolds, S1 cams, A568 with 3.77 FD and OBX.....and wrinkle blue goodness.

[Dan15]

I definitely didn't realize there was this much involved in changing the wiring harnesses. I'm currently gathering parts and information for putting a T3 motor into an 89' CSX and actually have quite a lot of different wiring harness options and I'm still not 100% sure which one would be the simplest to use in my scenario.

From reading through this thread it sounds like using an 88' or 89' SMEC engine bay harness and adding a portion of the RT underhood harness to it would be pretty simple and straight forward?


I Have the 89' CSX Harness of course.
I have an 88' CSXT Harness.
I have a 91' Spirit RT Harness.
And I probably have access to quite a few other harnesses if there is a different one that would be the ideal harness for my conversion.

Thanks in advance for the input.

It will be pretty sweet to have this many T3 CSX's around. From what I know of the top of my head there would be your 87' T3 CSX, Jackson's 89' T3 CSX that he plans to convert into being a replica of the 90' Prototype CSX and I'm planning to leave mine the factory appearing 89' with all gold and red engine bay parts to match.

[Pat]

The '89 CSX VNT is already SBEC. Converting that harness to t3 would not be difficult at all. I converted a '90 VNT Shadow to t3 and it was not nearly the job that converting my '88 SMEC Shadow was.

[DOHCRT]

The '89 CSX VNT is already SBEC. Converting that harness to t3 would not be difficult at all. I converted a '90 VNT Shadow to t3 and it was not nearly the job that converting my '88 SMEC Shadow was.

Yes to this, I converted my CSX-T using a spare 89 CSX harness and it was nearly plug and play.

[DOHCRT]

It will be pretty sweet to have this many T3 CSX's around. From what I know of the top of my head there would be your 87' T3 CSX, Jackson's 89' T3 CSX that he plans to convert into being a replica of the 90' Prototype CSX and I'm planning to leave mine the factory appearing 89' with all gold and red engine bay parts to match.

There are actually quite a few other TIII "P" bodies out there. Cindy had/has Neil's old one and she has the Birthday car. One of the CSX prototypes is in Tempe, I have an 88 "T" that I converted about 10 years ago.

The easiest way to convert is to use the 89 CSX harness and parts from a junk 91 R/T harness. (try to use a hacked 91 harness so you don't destroy a good R/T harness.)