Cooked GT Headlight Wiring!
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Thread: Cooked GT Headlight Wiring!

  1. #1
    Super Moderator Ooooner's Avatar
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    Cooked GT Headlight Wiring!

    After going awhile with no high beam headlights then running just one headlight on my 73 GT, I figured it was time to rewire my headlights.

    I bought a new headlight wiring harness from Keith Lundholm. Well worth the price! Professionally done.

    Anyway, after pulling the old harness out, this is what I found! Fire waiting to happen. I know this subject has been talked about a lot, but the proof is in the pudding! Change yours if you haven't already! I probably waited longer than I should have.
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    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    Senior Member crliwa's Avatar
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    Just in time.... Let us know how much time and effort installing the new harness takes you.
    The Scifi Guy likes this.
    Craig Roberts

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    What's a Nopel? Marc's Avatar
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    Agreed. Well worth the effort. That happened to me during my build & the wires crumbled/disintegrated in my hands.

    But I wasn't as lucky as you because Keith wasn't in the harness building world yet and bought a harness through Splendid parts. Professional quality, but every instruction was in German. However, it took me 3x longer to translate the instructions than the install of the harness!
    soybean and The Scifi Guy like this.
    50 years and counting. GT back on the Road 10/21/2014!

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    Super Moderator Ooooner's Avatar
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    Quote Originally Posted by crliwa View Post
    Just in time.... Let us know how much time and effort installing the new harness takes you.
    Not done yet but its taken a good 4 days work, spread out over a couple of weeks. I took the mechanisms out and cleaned them up, replaced the micro switches, greased the rotating joints with white lithium grease, etc. So, it's taking probably longer than it should but I'm taking my time and trying to do it the right way. While I'm in there, may as well fix stuff!
    Last edited by Ooooner; 06-05-2019 at 11:56 AM.
    soybean, The Scifi Guy and The Cub like this.
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    Super Moderator Ooooner's Avatar
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    Quote Originally Posted by Marc View Post
    Agreed. Well worth the effort. That happened to me during my build & the wires crumbled/disintegrated in my hands.

    But I wasn't as lucky as you because Keith wasn't in the harness building world yet and bought a harness through Splendid parts. Professional quality, but every instruction was in German. However, it took me 3x longer to translate the instructions than the install of the harness!
    Marc, I am lucky that Keith makes them now. I guess I could have made a new one myself but that would have been a pain in the ole butt. I saved a lot of time by just buying the harness.

    Keith's headlight harness goes all the way back to the fuse box under the dash. No splicing. BUT, it's one royal pain in the ass to fish the wires through the fuse box. I cut the old wires off at the firewall and used those wires to pull the new ones to the right terminal connections on the fuse box. I just matched up the correct new wires as the are color coded the same as the old ones. I did have to unbolt the fuse box and drop it down but that's no big deal.

    Also, while I was in there, I found a couple of bad spade connections. The connecters had become brittle and broke and were loose so I just replaced them with new ones. It was a tight space but I got it done.

    I also removed the drivers seat so I could lay on my back the best I could while working on it.
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    Opeler
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    What is the condition of your GT fuse Box?

    Excellent wiring links with pictures for assembly:
    https://www.opelgt.com/forums/1d-wir...ml#post1025257

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    Super Moderator Ooooner's Avatar
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    Quote Originally Posted by Lindsay View Post
    What is the condition of your GT fuse Box?

    Excellent wiring links with pictures for assembly:
    https://www.opelgt.com/forums/1d-wir...ml#post1025257
    The link you sent was great! Thank you.

    The fuse box is in excellent condition. Still has the cover that goes over the fuses. Not broken!
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    2000 Post Club soybean's Avatar
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    Quote Originally Posted by Ooooner View Post
    The link you sent was great! Thank you.

    The fuse box is in excellent condition. Still has the cover that goes over the fuses. Not broken!
    But you're havin FUN, HUH Roy, Told ya, ooldeles of "FUN" Jarrell
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    You lose your dreams, you lose your mind. (The Rolling Stones)

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    Super Moderator Ooooner's Avatar
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    Quote Originally Posted by soybean View Post
    But you're havin FUN, HUH Roy, Told ya, ooldeles of "FUN" Jarrell
    Oh hell yea! Having a blast! But in a strange way, satisfying.
    soybean likes this.
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    Super Moderator Ooooner's Avatar
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    Here we go! I've got all the wiring completed and worked a few bugs out. BUT... The white dash light, which comes on when the headlights are not locked in place, comes on when the headlights buckets are locked in the down position.

    New wiring, new micro switches... I'm thinking I wired a micro switch wrong which I believe is on the passenger side. This is a 73 GT...
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    2000 Post Club soybean's Avatar
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    Quote Originally Posted by Ooooner View Post
    Here we go! I've got all the wiring completed and worked a few bugs out. BUT... The white dash light, which comes on when the headlights are not locked in place, comes on when the headlights buckets are locked in the down position.

    New wiring, new micro switches... I'm thinking I wired a micro switch wrong which I believe is on the passenger side. This is a 73 GT...
    Do you have a wiring diagram? I think you are correct on the passengers side switch. I need to look at my wiring diagram which is down at the Shed to be certain. I can look now if you need it tonite. I'm through for the day. Jarrell
    You lose your dreams, you lose your mind. (The Rolling Stones)

  14. #12
    Opel Key Master opelspyder's Avatar
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    Three wires for the passenger side switch, White/yellow goes on N.O, brown on N.C., gray/green on C
    Driver side micro switch left hand side looking at the back of the mechanism Red/Black go on N.C., Brown/Black go on C

    These mean
    Normally Open
    Normally Closed
    Common

    The switches will have these markings on them
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    2000 Post Club soybean's Avatar
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    Quote Originally Posted by opelspyder View Post
    Three wires for the passenger side switch, White/yellow goes on N.O, brown on N.C., gray/green on C
    Driver side micro switch left hand side looking at the back of the mechanism Red/Black go on N.C., Brown/Black go on C

    These mean
    Normally Open
    Normally Closed
    Common

    The switches will have these markings on them
    73 Fsm shows starting at Rt side headlamp, (12Brown, 12 white,12 yellow.) Main headlights
    12 brown is ground, attached to Headlamp indicator switch (micro?),Passenger side 2 wires from micro 1 12wht/yel goes into Headlamp relay. The other side of the same switch, 12 Gray/grn runs back to Headlamp Ind 1 side, other 12 brown /Blk runs to Green plug in, runs 18 brown/blk to drivers side Headlamp ind switch, comes out as 18 blk/ red, runs to 15 amp fuse, 3rd from right on fuse block. Hth Jarrell
    Last edited by soybean; 06-06-2019 at 07:36 PM. Reason: Keiths wiring is same color code
    You lose your dreams, you lose your mind. (The Rolling Stones)

  16. #14
    Super Moderator Ooooner's Avatar
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    Found the problem. At the fuse box, I guess I was messing with it so much, one of the hot lead spade connectors had come loose. Needle in a hay stack!

    One of the spade connectors wasnít seated properly in the plug but I would have never found it without help from Soybean. Inspiration! It really was like a needle in a haystack. Whew!

    Now on to figure out why the white dash light is on when the headlights are locked down... 🧐
    soybean likes this.
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    Opeler
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    Opel GT Color Wiring Diagrams

    https://www.opelgt.com/forums/1d-wir...tml#post217402
    https://www.opelgt.com/forums/1d-wir...tml#post217417
    Quote Originally Posted by Swiftus View Post
    Just saw this thread. Here is the digitization of the '73 harness that I made. Its a vector file, so it scales infinitely without deformation or pixelization.

    Attachment 29221

    HTH,
    Jay

  18. #16
    Super Moderator Ooooner's Avatar
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    Thanks for the links!
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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    You got instructions ?

    I only got the loom in the box...no instructions...I tried to install the looms in the new fuze box as they came out..but it still looks like a rats nest...I installed it but plan on taking it out and seeing if I can clean up the jumble of wires.,.
    I wish I took better notes as to the location of the wire looms...I am having trouble getting them in the correct places...over, under or thru...

    Joel

  20. #18
    Opel Key Master opelspyder's Avatar
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    Roy, if you donít care about the white light feature, you can disconnect the Red/Black wire or even the Gray/Green wire that connects to the dash. I personally donít even run that circuit in our cars because I think it is stupid. I need an indicator light to tell me my headlights didnít turn on?

    Most of the wiring goes to the rear relays of the fuse box. The white jumper from the headlights goes into a connector, and the Brown/Black wire goes into another connector as well. You have the brake master cylinder switch too that will go into a box connector. The micro switch wiring is downsized from 12 gauge that is not needed and helps immensely with routing and installing the harness.

    The only thing I canít do to make it easy is install it for you. Iíve been running this harness for 10 years in multiple restorations, but never said it is easy to do without some experience.
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  21. #19
    Super Moderator Ooooner's Avatar
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    Keith... Iím not complaining at all! I knew it was going to be a pain before I even started. I think thatís why I kept putting it off for so long. Hell, Iím happy just because you made the harness and not me! Itís just one of those things... There is a sense of satisfaction of getting it all working again. Needed to be done. Not sure Iíd want to do another one but if I did, it would be easier as I know now better what to do.

    If I canít get the white light to do what itís supposed to do, Iíll take your advice and disconnect it.

    Thanks for the tips! The harness was well made.
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    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

  22. #20
    Super Moderator Ooooner's Avatar
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    Found the reason the headlight indicator light on the dash was on when the headlights were in a locked position. The light should be on when the headlight buckets are not locked either up or down. On the drivers side, the outer micro switch was hooked up wrong. Had one of the connections on the wrong terminal. My bad....

    But little bugs are expected to be worked out due to human error (me &#128526.

    Everything is finally working again as if the car was new! Thanks Keith for the harness. Worked out great.
    Roy Bell
    1973 Opel GT
    Concord, North Carolina
    Carolina Opel Club

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