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  1. #1
    FEP Senior Member 86GTdriver's Avatar
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    Default 86GT Digitial Premium Radio Sound Wiring ?s

    I'd like to acquire the proper harness(es) that will take my 86GT Premium digital radio to straight base wires without cutting into the harness. I've looked across the internet, but can't seem to find the proper harness to match the connectors that are the opposite mating connectors to the ones on the dash radio portion of the harness, let alone how to bypass the dash amp properly. Can anyone suggest what to do? I'm very interested in doing this properly in case I ever want to put my OE radio and amp back into the car. Thanks!
    Last edited by 86GTdriver; 01-24-2020 at 07:48 PM.
    '86 Mustang GT T-Top, 5-lug Cobra brake swap done
    '96 Mustang Cobra 302rwhp 296rwtq, Sold and missed
    '11 Mustang GT/CS, Traded and will be missed
    '13 Taurus SHO, Performance Pack, hit and run, totalled
    '17 Fusion Sport, Livernois tune, Steeda CAI, Steeda Rear Swaybar, Big Mouth Ram Air, GFB+ valve, Steeda Catch can, TTR FMIC (Garrett Core)

  2. #2
    FEP Super Member gr79's Avatar
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    Default factory radio notes

    Have had many different radios in my 79 over the years. OEM was AM/FM std push button shaft mount.
    The dash oem harness is intact. Went with DIN. Cut the dash. Never went back. Too hard to work with non DIN.
    Had aftermarket. Factory Ford are easier to operate. Current is from 1992 connected to JBL 4 ch amp.

    May be able to help once the specific radio is id'ed.
    Face and rear connector type.
    Hard wired or back of radio plug in harness like M100.
    The later M100 type radio connection is common in late 80's thru 90's.
    Mid 80's is when both early and late type radios could be found installed. Regular and premium.

    Assuming is a DIN mount dash opening, square cut, no shaft knobs or dial.
    If the factory amp is always on, the radio may not have an amp section and will need ext amp.
    If radio can be played with amp off (under dash amp pull switch), it has internal amp.
    Removable factory radio pigtails can be found in self pic yards for a couple bucks. Early ones not so much.
    The wire codes are the hard part. Different radios can have same connectors but slightly different pin out functions.
    The speaker ones are usually the same pin outs. Radio power, lighting, memory wire color coding can change.
    Especially late 80's thru the 90's.

    Pics for reference only not endorsements.

    If hard wired radio plug has male bullet connectors, i have jammed butt connectors or the round end of a spade connector in there.
    And taped the heck out of it. Or use 3M Scotch-Loc splices tapped directly into the wiring.
    https://www.grainger.com/product/1A0...g!471571925921!

    A few examples
    https://www.installer.com/cars/by_car.php?car=ford
    https://www.installer.com/item/displ...php?it=71-1772

    M100 type
    https://www.installer.com/item/displ...php?it=71-1770
    https://www.ebay.com/itm/Factory-OEM...ty!48105!US!-1

    'Hard wired'
    http://vb.foureyedpride.com/showthre...I-do-with-this

    Commonly seen in mid 80's
    https://prestigemustang.com/images/F143168554.jpg
    https://picclick.com/FORD-Factory-Ra...295673906.html

  3. #3

    Default

    I believe the metra 70-1772 is the correct harness to fit factory radio plugs to your after market head unit. I have not been able to find a factory amp bypass harness.
    I believe I will have to cut the wires.

  4. #4

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    Ok, the metra 70-1772 is the proper harness to connect the new head unit to the existing wiring. However, it will not bypass the amp. After spending some time today, I believe the best thing to do is unplug the amp, and run new wires from the front speakers to the new head unit. This way you dont need to cut any wires at all, so they are all in place to return to original. The rear speakers were not amplifed, at least not on my car so I was able to trace them to the metra harness and reuse the existing wiring. The other plug on the harness has your power, lights, ground, and memory power. Easily converted with no wire cutting.

    Attached is a pic of the "premium" amp. Probably 10 watts/ channel.
    Last edited by tom's 86; 03-08-2020 at 07:23 PM.

  5. #5
    FEP Senior Member 86GTdriver's Avatar
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    Default

    I have the one from the very bottom link of gr79's post. The P/N on the unit is E5VF-188865-BA. I'm also looking for the amp bypass wiring harnesses too for this. There's just too much misinformation out there.
    Last edited by 86GTdriver; 03-22-2020 at 04:05 PM.
    '86 Mustang GT T-Top, 5-lug Cobra brake swap done
    '96 Mustang Cobra 302rwhp 296rwtq, Sold and missed
    '11 Mustang GT/CS, Traded and will be missed
    '13 Taurus SHO, Performance Pack, hit and run, totalled
    '17 Fusion Sport, Livernois tune, Steeda CAI, Steeda Rear Swaybar, Big Mouth Ram Air, GFB+ valve, Steeda Catch can, TTR FMIC (Garrett Core)

  6. #6
    FEP Senior Member 86GTdriver's Avatar
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    Default

    I was on the 12volt earlier today and was trying to figure out two things:

    1. Where is the aftermarket stereo going to ground as there's not a ground wire on the OEM plug.

    2. There doesn't seem to be a illumination dimmer wire either.


    Can anyone tell me how to solve this? It doesn't match up with the drawings posted here for '86 (of course). While using the drawings though on pg 14, A 138-143, I can't figure out what things like 'Foot Control Switch', 'Interior Lamp Switch' and 'Radio Antenna Switch'. I'm guessing these are all 12V Switched wires, but as to what they're for I'm unsure in reference to what I am looking for above. I'm also guessing 'Speaker Return' from the factory amp is a ground, but it only runs from the OEM radio to the amp and not to anything else. Which is strange to me because 'Speaker Return' normally is used to reduce possible hum/buzz on the speakers. I've often seen this wired to the same ground point as the feedback resistor and input ground connect to the power ground. I know this is OEM and it's ancient, but I just don't see any way to hook up an aftermarket radio to this 'correctly' and bypass the factory amp.
    Last edited by 86GTdriver; 03-25-2020 at 06:20 AM.
    '86 Mustang GT T-Top, 5-lug Cobra brake swap done
    '96 Mustang Cobra 302rwhp 296rwtq, Sold and missed
    '11 Mustang GT/CS, Traded and will be missed
    '13 Taurus SHO, Performance Pack, hit and run, totalled
    '17 Fusion Sport, Livernois tune, Steeda CAI, Steeda Rear Swaybar, Big Mouth Ram Air, GFB+ valve, Steeda Catch can, TTR FMIC (Garrett Core)

  7. #7
    FEP Senior Member 86GTdriver's Avatar
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    Default

    Based on what I've read here and my own research, I've learned that (I think) on small gray 4-pin (3 wires though) C708 connector:

    LG/YLW is 12V Constant/Hot at all times
    YLW/BLK is 12V Switched/ACC
    Lgt Bl/Red is Illumination (and dimmer possibly?)

    I might have the 12V switched and constant backwards. Can anyone confirm since the descriptions on the schematics are kind of vague?

    I am still not understanding this whole common ground thing. It appears each front speaker has a negative wire that feeds back via the Speaker Return wire between the OEM radio and OEM amp, then the amp has a ground wire coming off of it that grounds to chassis based on pictures I have seem of it. Still unsure if there's any relation between the two.

    Essentially I am still pondering if the Illumination wire will dim when the parking lights/headlights come on and where to place the ground for the HU I want to put in. Then delete the OEM amp entirely, removing it's small harness, then running all new speaker wires just to save myself the hassle. At this point, I just want to ensure the HU gets functioning properly.
    Last edited by 86GTdriver; 03-28-2020 at 10:21 AM.
    '86 Mustang GT T-Top, 5-lug Cobra brake swap done
    '96 Mustang Cobra 302rwhp 296rwtq, Sold and missed
    '11 Mustang GT/CS, Traded and will be missed
    '13 Taurus SHO, Performance Pack, hit and run, totalled
    '17 Fusion Sport, Livernois tune, Steeda CAI, Steeda Rear Swaybar, Big Mouth Ram Air, GFB+ valve, Steeda Catch can, TTR FMIC (Garrett Core)

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