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1969 GT 500 park lamp/signal ground ?

Discussion in '1965-1970 Shelby Mustang GT350 & GT500' started by Doug D, Dec 14, 2011.

  1. Dec 14, 2011 #1
    Doug D

    Doug D Active Member

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    I'm stumped.

    Got all the exterior lights working perfectly...even the rear sequential signals.... except the front park/signal lamps.

    The front park/signal lamps work only if I apply an independent ground.

    How are these lamps supposed to be grounded?

    I'm using both Mustang and Cougar wiring diagrams hoping to find a clue. The Cougar diagrams show two variations of the front park/signal lamp circuit one of which comes close to what I have on this car but isn't an an exact match.

    The diagrams for a regular Mustang show front park/signal lamps with 3 wires...one of which is clearly a ground.

    The lamps on this car have two wires (blue and black) corresponding to the hi/low filament of the bulb. There is no ground for the socket and the housing is mounted in fiberglass.

    What am I missing?

    100 thanks

    Doug
     
    Doug D, Dec 14, 2011
    Doug D, Dec 14, 2011
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  2. Dec 14, 2011 #2
    DJR

    DJR Well-Known Member

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    Your right. Since it is mounted in fiberglass the lamp body needs a ground wire. It attaches to the one of the screws that mount it to the valence. Don't have a pic right now but someone on here will get you one.
     
    DJR, Dec 14, 2011
    DJR, Dec 14, 2011
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  3. Dec 14, 2011 #3
    Doug D

    Doug D Active Member

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    Ok, thanks for the reply and confirmation that I wasn't losing my marbles. If nobody posts a pic I'll work up a nice sanitary ground.

    Cheers
    DD
     
    Doug D, Dec 14, 2011
    Doug D, Dec 14, 2011
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  4. Dec 15, 2011 #4
    Doug D

    Doug D Active Member

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    More info.....

    You guys probably know all about this but I thought it I'd throw it open for comment.

    I had an opportunity to compare this car (6/69 build) with an early car (1/69 build). Both GT500 convertibles.

    The later car...the one I'm working on...has two-wire park/signal lamps. The front lamp harness is grounded at two points at the bottom of the radiator core support. I'll run my two new ground wires to the same ground points.

    The earlier car has 3-wire park/signal lamps and the front lamp harness does not have any grounds at the bottom of the core support.

    I suspect this relates to the two different wiring schemes shown in the Cougar wiring diagrams.

    Cheers
    DD
     
    Doug D, Dec 15, 2011
    Doug D, Dec 15, 2011
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  5. Dec 15, 2011 #5
    Bob Gaines

    Bob Gaines Well-Known Member

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    This is not a early or late issue or a cougar vs mustang issue. All 69/70 Shelby's ground the same way and it isn't on the radiator support . Most likely you are using the wrong parklight pigtail because they all plug into the Mustang headlight harness or there has been some previous owner intervention in the past. The park light plug that is incorporated into the park light housing assembly will have a loose grounding terminal that grounds to the stud closest to the radiator suport side. The terminal is attached with a Zinc gold nut on top of the shell nut that is already mounted that secures the housing to the fiberglass valance . The ground wire is connected to the 3 terminal plug that plugs into the Mustang headlight harness that the 69/70 shares with the Mustang. I hope these pictures help.Sorry but the only pictures handy were photo shop sourced . You may have to down load them and "open with" a compatable picture program. Bob
     

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    Last edited: Dec 15, 2011
    Bob Gaines, Dec 15, 2011
    Bob Gaines, Dec 15, 2011
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  6. Dec 15, 2011 #6
    Doug D

    Doug D Active Member

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    Ahhhhhhhh. OK. Suddenly it all makes sense.

    The wires that somebody (not me!) ran to the core support are supposed to go to the lamp mounting bolt. Grrrrr! I should've figuerd this out on my own....but it looks like they belong there so I didn't give it enough thought.

    Now I can go remove the additional ground wires that I just made up and installed :rolleyes:

    Eventually I'll get to the end of the road on this car. This is the last (I think) wiring issue that I have to straighten out.

    Many thanks,

    Doug
     
    Doug D, Dec 15, 2011
    Doug D, Dec 15, 2011
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