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  1. #1

    Default 84 Mustang GT wiring harness

    My harness lost the insulation around the wires. Especially where the wires go into the plug. UGH! I tried to rig it with electrical tape, but now the tach won't work. Anybody got one they could part with. Or, does anybody know which year truck will work? Help!
    Mike
    Sunbury, PA
    79 Coupe, 357W balanced, AFR 185s, Vic Jr, Holley 750, C4 roller, 4.56 8.8 spool, 26 MT Drags, 11.00 @ 123
    83 Mustang GT, 88 GT engine, T5

  2. #2
    FEP Super Member Travis T's Avatar
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    Default

    Is it the car side or the engine side? I'm replacing mine now and it is really hard to find a good one. If it is only one connector, Google Motorcraft pigtails. Connectors with a short section of wire are available to splice in.
    1984 Mustang GT owned since 1991 (first car). Mercury Mountaineer GT-40P engine, some suspension mods, currently undergoing a five lug SN95 brake upgrade and more suspension mods. Some minor body and interior mods have been done as well.

    2004 GT convertible, 2001 Taurus LX, 1994 F150, 1950 F-1 Ford Pickup

  3. #3

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    It is both actually. The plugs going into the Duraspark box are where its worse.
    79 Coupe, 357W balanced, AFR 185s, Vic Jr, Holley 750, C4 roller, 4.56 8.8 spool, 26 MT Drags, 11.00 @ 123
    83 Mustang GT, 88 GT engine, T5

  4. #4
    FEP Super Member 84StangSVT's Avatar
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    Welcome to the club as mine is really bad there and so are many others. The green wire that is on that plug is for the tach dwell and either it broke while you were trying to tape it or it is still grounded somewhere else......ran into the same issue with mine.

    A good used harness is hard to find for these cars and I'm not of much help to say which or if a truck harness will work. I'm probably just going to end up buying the connectors I need and custom making a new engine harness.
    Brock
    1984 Mustang LX Convertible 3.8L V-6/Auto (SOLD)
    1984 Mustang GT Hatchback 5.0 V-8/5 Speed

    I'm an FEP Supporter and proud of it. Are you?

  5. #5
    FEP Senior Member Matt J's Avatar
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    I'm not sure 100% which part of the wiring harness you're referring to, but you mentioned the ignition...you can get a new connector for the ignition module with pigtails sticking out of it from most auto parts stores, I got one from NAPA as I recall. 20 minutes with my soldering gun and some heat shrink to cover the connections and it was a nice clean job. You can get most connectors that you need from parts stores if you have a bad one (or ten). Never hurts to ask, and if you get the right person behind the counter they sometimes know what works with what in terms of interchangeable parts.

  6. #6
    FEP Super Member Travis T's Avatar
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    I can tell you at least as far as the body harness under the hood that there are some significant differences between 84s and 85s. I went and looked at an 85 I'll be getting a harness from and I think it can be made to work, but it won't be a plug and play. 83s may be closer to right for an 84.
    1984 Mustang GT owned since 1991 (first car). Mercury Mountaineer GT-40P engine, some suspension mods, currently undergoing a five lug SN95 brake upgrade and more suspension mods. Some minor body and interior mods have been done as well.

    2004 GT convertible, 2001 Taurus LX, 1994 F150, 1950 F-1 Ford Pickup

  7. #7

    Default

    Put up a parts wanted ad or go check napa for the connectors.
    Cheers!

    Mike (TopGear85)



    Have:
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    90GT-Oxford Wht,5spd

  8. #8

    Default

    I don't have 100 posts yet to place in classified, otherwise I would. I also requested info regarding swapping in an 80's ford truck harness too.
    79 Coupe, 357W balanced, AFR 185s, Vic Jr, Holley 750, C4 roller, 4.56 8.8 spool, 26 MT Drags, 11.00 @ 123
    83 Mustang GT, 88 GT engine, T5

  9. #9

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    The only time you need 100 posts is to SELL parts.
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  10. #10

    Default

    I put a harness in from an early to mid 80's truck that had a 302. If the Duraspark box has the blue connection then take that too. The harness I took had one connector that was different but I spliced the wires into my old plug and it works perfectly. The harness is a bit longer because of the bigger engine bay.
    1985 Mustang GT 5speed LRB with Ford Racing M-6007-X302, Performer RPM, Holley 670 Avenger carb, BBK headers with H-pipe, B&M short throw
    1986 Mustang GT (parts car)
    1986 LX Coupe 4cyl, 4speed, LRB

  11. #11

    Default

    Thanks. I'll have to look for a mid eighties truck. Otherwise, did anybody fabricate their own harness from pigtails? what pigtails do I need. BTW, it's a non-AC 84GT car. Thanks,
    Mike
    79 Coupe, 357W balanced, AFR 185s, Vic Jr, Holley 750, C4 roller, 4.56 8.8 spool, 26 MT Drags, 11.00 @ 123
    83 Mustang GT, 88 GT engine, T5

  12. #12

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    Feeling Good! I sourced some pigtails from local the u pull it (the three cavity and the four cavity) that were in good shape, and I dug through the 86GT wiring tote and found an 8 pin. I bought some good wire and fabricated a good harness using the old one as a guide. I also learned how to solder wires together with shrink wrap instead of wire connectors. thanks guys. I just fired it up and everything works! It took about 6 hours over the weekend. I'm glad I did it.
    Mike
    79 Coupe, 357W balanced, AFR 185s, Vic Jr, Holley 750, C4 roller, 4.56 8.8 spool, 26 MT Drags, 11.00 @ 123
    83 Mustang GT, 88 GT engine, T5

  13. #13

    Default

    Anybody else do their own harness?
    79 Coupe, 357W balanced, AFR 185s, Vic Jr, Holley 750, C4 roller, 4.56 8.8 spool, 26 MT Drags, 11.00 @ 123
    83 Mustang GT, 88 GT engine, T5

  14. #14

    Default

    That's the best way to do it. Did you keep all of the wire colors the same?
    '88 Mustang GT convertible, T5, 3.08:1 gears. 5.0 Explobra Jet: A9L Mass Air conversion, Fenderwell Mac cold air intake, 70mm MAF meter = 4.6 T-Bird/Cougar housing + '95 Mustang F2VF-12B579-A1A sensor, aftermarket 70mm throttle body and spacer, Explorer intakes, GT40P heads with Alex's Parts springs and drilled for thermactor, Crane F3ZE-6529-AB 1.7 "Cobra" roller rockers, Ford Racing P50 headers, Mac H-pipe, Magnaflow catback, Walbro 190 LPH fuel pump, UPR firewall adjuster and quadrant with Ford OEM cable, 3G conversion ('95 Mustang V6), Taurus fan, rolled on Rustoleum gloss white paint...
    Past Four Eyes: Red well optioned '82 GT 5.0, Black T-top '81 Capri Black Magic 3.3L 4 speed, Black T-top '84 Capri RS 5.0 5 speed.Over 200,000 miles driven in Four Eyes, and over 350,000 in Fox Body cars.

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