1987 vs 1988 5.0 engine harness June 26, 2012, 10:26:13 PM I'm having virtually no luck finding a 1987 5.0 engine harness for a 3.8 to 5.0 swap. I did find a 1988 5.0 harness. Is it possible to use the 88 harness in my 87, and if so is it worth the headaches? Quote Selected
1987 vs 1988 5.0 engine harness Reply #1 – June 26, 2012, 11:23:52 PM To clarify, you are only asking about the engine harness, not the ecc portion which goes though the fire wall and into the engine compartment? If that is the case, the previous application of the engine harness is not as critical. Granted my car is an '86, but the engine harness is from and '89 Mustang 5.0. It's an original 5.0 vehicle, but the engine harness had deteriorated due to heat and age. I swapped it out for the Mustang unit. Everything plugged in, there were no issues. There may be color differences between the wires, but it's not a functional change.My understanding is critical part for a 5.0 swap to an 87 is the harness is runs from the EEC though the fire wall into the engine compartment. Apparently there are wire color coding differences between 87 & 88, which can make putting an '88 harness into a 87 more complicated. Quote Selected
1987 vs 1988 5.0 engine harness Reply #2 – June 27, 2012, 09:57:23 AM There are also plug differances between the 87 and 88 (the connections that go between the harness and the plugs that come from the drivers side that run the gages exc.) Quote Selected
1987 vs 1988 5.0 engine harness Reply #3 – June 27, 2012, 12:55:28 PM Even having eatc vs standard heater jas different plugs, as does the digi dash.You'll have to get your hands dirty if the stars don't align perfect, but its not bad. Quote Selected
1987 vs 1988 5.0 engine harness Reply #4 – June 27, 2012, 02:30:36 PM Quote from: Haystack;393310Even having eatc vs standard heater jas different plugs, as does the digi dash.You'll have to get your hands dirty if the stars don't align perfect, but its not bad. This is true....personal experience. I've got an '88 engine harness for a full optioned car in excellent shape if you decide to mod one... Quote Selected
1987 vs 1988 5.0 engine harness Reply #5 – June 27, 2012, 03:00:46 PM Thanks for all the info. I apologize for my extreme lack of knowledge on this, but the last swap I worked on back in the 70's involved a carburetor and ignition points.I'm just beginning to gather parts for this swap. I'm basing my EFI/carb decision on whether I can find the necessary harness(es). I'd really prefer going EFI based on what I've been reading here for the past few years. It sounds like I'll need to find (ideally) an '87 EEC harness, an '87 engine harness, and the correct EEC to make this 'plug-n-play' from an electrical standpoint. I've also read about re-pinning the 'wrong' harnesses. Is this a major PITA, or something that somebody with average mechanical and electrical skills cound handle?Sorry for all the questions. I finally got the go-ahead from "she-who-holds-the-checkbook" to start picking things up, and want to get moving before she changes her mind :) Quote Selected
1987 vs 1988 5.0 engine harness Reply #6 – June 27, 2012, 07:08:33 PM I have worked around electrical designs and blue prints, so I wouldn't consider it to be that bad. Reall you would want a bunch of extra wire, just in case, maybe some soldering/pin or connector swapping, and a evmt for all year cars.When you really break it down, there's only a couple parts to the electrical system of the car. Chassi(you shouldn't even have to touch, except maybe a hot key on splice or something) computer wiring(mostly just the plug from computer to the "salt and pepper" connectors, and a couple grounds/connectors at the sensor's/engine.What will throw you off is the wires change color and configuration by ertain years, generally on small things that don't much matter. So your computer plug might have a different pinout/connector then your engine harness. Depending on what car your starting from and turning into, you might have to replace some under dash wiring too, really just depends. I actually have started to quite enjoy trouble shooting electrical.Basically, see if the plugs are the same, or similar, and you'll have a fairly good idea how much work you'll have. I think you should be fine to swap just the computer harness, as long as you hook your power/ ground wires into the existing harness correctly. Quote Selected
1987 vs 1988 5.0 engine harness Reply #7 – June 28, 2012, 08:40:01 AM Just to be sure I'm clear on what's what, my understanding is that the eec harness goes through the firewall and terminates at the 'salt and pepper shakers', and what I've seen called the 'engine harness' begins at the s&p shakers and runs around the engine bay. Am I even close? Quote Selected
1987 vs 1988 5.0 engine harness Reply #8 – June 29, 2012, 10:22:31 AM So why can't a guy just use the engine harness and EEC harness from a 5.0 Mustang? When I switched from a 4 cylinder over to a 5.0 in my Coupe it was plug and play. There are basically three harnesses I needed: the oxygen sensor harness, the engine harness, and the EEC harness. None of this interconnected with the chassis harness which is what I am suspecting the T-Bird EEC harness does?I am installing the Painless Wiring harness on my dad's 69 fastback for his injected 393. This harness is based on the Fox Mustang 5.0 harness. It has the oxygen sensor harness, engine harness, and EEC harness all in one. It was not cheap ($600 or so) but its all brand new and the plugs on it are identical to the factory connectors that came on those cars so we can use all the stock sensors. Not sure if this would be some kind of solution to the OP's problem or not. If I ever converted my 83 Bird over to fuel injection this would be the only way I would do it.Darren Quote Selected
1987 vs 1988 5.0 engine harness Reply #9 – June 29, 2012, 03:16:25 PM Are the engine harness and the eec harness what meet at the salt and pepper shakers? Quote Selected
1987 vs 1988 5.0 engine harness Reply #10 – June 29, 2012, 03:56:52 PM As long as you have wiring diagrams for what you're using it's not that much of an issue. Quote Selected
1987 vs 1988 5.0 engine harness Reply #11 – June 29, 2012, 05:16:35 PM kevbey,Yes.Darren Quote Selected
1987 vs 1988 5.0 engine harness Reply #12 – June 29, 2012, 07:00:35 PM At my last work, we converted a 2.3 turbo sand rail over using a turbo couple wiring harness and fast efi. The mechanics didn't want my help trouble shooting when it wouldn't start, but after a week or two they let me pull up some wiring diagrahms and information for them.The connector on the tps was cut, so they just put some flat blade connectors on it and wired it in wrong. When I brought up that this is one of only 6 wires required to start, pulled up a diagrahm for them, and they had it running in 10 minutes.It was pretty funny when they asked me how many aftermarket computers I have delt with. I answered with none, only read about them on the internet. Fun .Oh and btw, fast sent many messages back. And forth for this whole 2 week period and were very helpful, but they had them replace the pip and msd coil before they would take the computer back for a check and re-flash of firmware. The mechanics were sitting there complaining about having to pull it out and everything before I mentioned the tps. Quote Selected
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