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1990 SC 5spd engine swap 5.0 HELP!

2K views 9 replies 3 participants last post by  S4gunn 
#1 ·
Before you go there, yes I've done a search and it has gotten me this far.

I know it won't happen here as much as on SCCOA but the engine was in pieces and had a split crank when I got it so I don't want to rebuild it as I already have a rebuilt 5.0l in my sport w/ HCI waiting for a donor car and this has everything I wanted for that car and then some.

Now to the good part. I have already re-pinned the ECU harness (just need to run the wires for the extra 2 injectors) and am wondering if I need to wire in the DLC+ and DLC- wires since this ecu was not pinned for them. Also, is it possible to splice the dizzy into the EDIS wires or do I need to cut up the 5.0 body harness and transplant those wires into the SC?
 
#3 ·
Because the SC body harness has the ABS wiring and other integrated things that I'd like to keep on the car that the 5.0 sport body harness doesn't. Plus I'd rather not remove harnesses as much as possible on a 25+ year old car. They get brittle and usually never fit quite right after you do that. I figured this would be the easier route and then I can always drop a motor in the sport and kick it down the road to some teenager that wants something different than a mustang. :D
 
#4 ·
If the goal is to NOT molest the engine harness wires as much as possible, why not run fresh wires for the Distributor instead of relying on the old/brittle wires in the harness?
While it won't look as clean/stock looking, there will be 2 fewer points of failure with my suggestion (the wire itself and where the engine harness plugs into the body harness).

-g
 
#5 ·
I didn't mean use the body harness, I meant use the complete 5.0 engine harness and ECM. You don't need to change the body harness, just change the ECM and engine harness, and keep your body harness to keep your ABS, auto ride control, etc. You will have to re-pin some things where they go into the dash harness just because 90 and 91 were wired slightly differently, but trying to modify an SC harness to run a 5.0 when you have a 5.0 harness sitting right there is making a lot of un-necessary work for yourself.
 
#6 ·
I will be using the 5.0 engine harness that plugs into the harness that goes through the firewall into the ECU. I already re-pinned the ECU to accept this. However, for whatever reason the engineers thought it was necessary (maybe because the SC used edis and it was easier to just designate that body harness to that body) they put those wires in the harness that also runs the arc, abs, headlights etc. I'm just curious if I have to cut up another harness to get those wires out that run the dizzy so I can install them in the SC to finish the install. The body harness ties into the ecu harness that goes into the firewall. I just don't want to cut up harnesses if I don't have to but I will if that is the best way.
 
#7 ·
What ECM are you using? If you are trying to use the SC ECM to run a 5.0, then you are likely in uncharted territory. If you are planning on using the 5.0 ECM out of the 91, you can save yourself a bunch of headaches by using the harness that goes through the firewall from the same car. This will pretty much guarantee that all the wiring from the ECM to the engine is correct, and then it is just a matter of re-pinning some connectors to the dash and body harnesses.
 
#8 ·
I'm using T4M0 out of 5spd GT Mustang. I already re-pinned the ECU harness to match the pinout to run the engine with this ecu and I prefer to keep this harness in the vehicle since it has more than what the sport/lx 5.0 bird harness could ever hope to be. I will be able to run the e-fan and abs without any trouble with the harness in the car and the mustang ecu.

I really just want to know about the dizzy and the DLC wires that are on 91+ birds and sn95 mustang. For some reason the 89-90 SC didn't have the DLC (diagnostics) positive and ground wires run through the ecu? Is it necessary to have them there? Will I be able to read codes?
 
#9 ·
The T4M0 will not work with the auto ride control. Other than that, the pinout of the ECM connector is basically identical to the 91-93 5.0 MN12 ECM. If you use the harness going through the firewall from the 5.0 car, then it will definitely run. Like I said, you will have to re-pin some things to get everything working, but all the engine controls part will already be done for you. If you insist on running the SC firewall harness, then what you have to do is make sure that every wire coming off the ECM makes its way to the correct location on the other side. If the wires for the distributor are not in that harness, then you will need to add them. If the wires for the DLC are not in that harness, then you will need to add them. If you wind up with other un-used wires in that harness, you can move them to the correct pin on both sides to make the connection, but make sure you keep track of what wires you use for what, otherwise you won't know what wires are what if you ever have to diagnose anything.
 
#10 ·
I'm 99% sure I did what MM is suggesting above when I redid my took my 95 tbird 3.8 and swapped in a 5.0 from a 93 donor -- I took both the engine harness AND the harness that goes into the car through the big whole from the donor car.

There were a few wires I had to track down b/c the 93 5.0 engine harness did not have any provision for a CCRM but I didn't care that these things were wired separately (fan, etc.).
The most important feature of the body harness (the one that goes through the dash and to the power) was for ABS and I can confirm from experience that ABS still works.
http://forums.tccoa.com/8-engine-5-...1995-3-8l-n-5-0-swap-diy-lessons-learned.html

BTW, I found a comparison of the ECU plug pinout between a 93 Tbird and a 95 Mustang when I started with QH and was deciding which ECU to use (I got a good deal on a 94-95 Mustang ECU -- a W4H0 which is uses the same strategy CBAZA as the T4M0).
If you look at the diagram, you'll see that there were some small pin differences which in my case didn't matter but in yours you might care about (ride control vs. Hi fan, for example).
http://tccoa.com/forums/12-eec-tuning/151785-few-questions-ford-5-0-302-quarterhorse.html
 
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