Headlight relays on a car with concealed headlights

Electrical & Ignition

  1. 1972GY8SE

    1972GY8SE FBBO Gold Member FBBO Gold Member

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    Just thinking out-loud--If the green wire at the dimmer switch was hot all the time (and it should not be), would the mechanical dimmer switch leak voltage to both headlamp circuits?
     
    Last edited: Mar 6, 2021
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    • Kern Dog

      Kern Dog FBBO Gold Member FBBO Gold Member

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      More weirdness.

      I pulled the carpet back and saw a melted plug for the dimmer switch that I didn't notice before. It obviously still worked but I may replace it anyway. I swapped in a spare dimmer switch and tested it. It was the same as before.
      With the key ON and headlights shining, I pulled the dimmer switch plug and the headlights shut off.
      I pulled the instrument cluster and pulled the headlight switch plug....and the lights stayed ON.
       
    • Kern Dog

      Kern Dog FBBO Gold Member FBBO Gold Member

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      I'm going to ask this dumb question again....
      I'm guessing that I leave the ignition on, lights on and pull fuses until the lights shut off? The fuse that is last pulled is the circuit that is responsible?
       
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      • 1972GY8SE

        1972GY8SE FBBO Gold Member FBBO Gold Member

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        You're on the right path, you should replace the melted connector.
        Is the green wire at the dimmer switch hot at all times?
        AKA "beam selector switch"
         
        Last edited: Mar 6, 2021
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        • Kern Dog

          Kern Dog FBBO Gold Member FBBO Gold Member

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          I'll know once I get a bulb for the test light.
           
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          • Nacho-RT74

            Nacho-RT74 FBBO Gold Member FBBO Gold Member

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            Headlights are not fused. Definitelly you got some source keeping hot the green wire and is related to the RUN circuit. Check the hideaways relay. Green and blue wire could be shorted out somehow.
             
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            • Kern Dog

              Kern Dog FBBO Gold Member FBBO Gold Member

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              I had regular gauges in 2013 when I tried relays the first time and had similar problems.
              The power inputs for the cluster are in my auxiliary fuse panel. That panel is for all non stock additions. Gauge panel. Stereo. Trunk latch. Air/fuel gauge. Auto dimming rearview mirror. The stock fuse panel was a 6 fuse unit, I swapped in a 7 fuse unit from a mid 70s A body.
              I'm willing to try everything.
               
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              • Kern Dog

                Kern Dog FBBO Gold Member FBBO Gold Member

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                Terminal X is a 16 ga Violet wire, Terminal Y is a 16 ga red wire. Both go to the dimmer switch. This must be low beam & high beam.
                The 3rd wire from the dimmer is light green and goes to the concealed lamp relay. At that same terminal, another light green wire goes back to the headlight switch.
                Looking deeper, the H/L door relay looks to be fed by the voltage regulator and one of the alternator field wires.
                 
              • Kern Dog

                Kern Dog FBBO Gold Member FBBO Gold Member

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                The H/L door motor has 2 grounds. One ties in with the headlight ground wire loop, bolted to the firewall. The other ties into the high beam bulb socket. The 2 power feeds go through the firewall and to the relay.
                Here is a weird question. Does it matter which field wire is on which terminal on the alternator?
                 
              • Kern Dog

                Kern Dog FBBO Gold Member FBBO Gold Member

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              • 1 Wild R/T

                1 Wild R/T FBBO Gold Member FBBO Gold Member

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                You've made some good progress... You've eliminated the headlight switch & all the wiring forward of the dimmer switch... The headlight door relay looks promising If not that theres likely melted wires in the dash harness cross feeding the green wire... The green wire normally goes straight to the headlight switch but in this case it goes to the relay... Soooo disconnect the two green wires going to the relay & connect them to themselves... The doors won't open but what do the headlights do? If they are out the relay is the cause if not open the harness & inspect the wires...
                 
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                • 6PKRTSE

                  6PKRTSE Well-Known Member

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                  Yes, if I ever turned on my high beams after about 5 mines all my lights would go out and come back on almost like they were blinking.
                   
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                  • Crackedback

                    Crackedback Well-Known Member

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                    This is rules out the relay kit. If the wiring isn't connected to the switch there should be no voltage to trigger. Something is hunting as 1 wild R/T mentioned as well. It's leaking voltage from somewhere. I might suggest you start pulling fuses from the box to see if the lights go out. Then you can identify the circuit that is leaking. Now you get to hunt where the car is hunting... I feel for you because even though I'm good at this, I HATE doing what you are dealing with as well, searching for a leak/bleed in a circuit.

                    I didn't read many of the responses since my last post and it appears you may be on this track.

                    Leave the single driver side OEM plug on the headlight with the switch off, key on. Probe the terminals for voltage. The factory wires are violet low beam, Red high beam. I try to mimic my wires to the OEM, in this case I ran out of violet wire so low beam on his headlight plugs is green on my kit IIRC.

                    Is the green wire entering the dimmer switch dead when the key is on and unplugged? Sounds like the issue is in the cabin based on what was written above. If the dimmer plug is melted there may be a spot in the under dash harness that has melted ever so slightly to allow wires to touch causing a leak.
                     
                    Last edited: Mar 6, 2021
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                    • Crackedback

                      Crackedback Well-Known Member

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                      Yes, the switching mechanism hots one lead or the other, there is no neutral position where flow of current is blocked under normal operation.
                       
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                      • moparsaver

                        moparsaver FBBO Gold Member FBBO Gold Member

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                        Electric gremlins are the worst. I feel your pain man. Attached are the wiring diagrams.
                        3066CED7-AFE0-4E1F-A084-07D0A7384102.jpeg B468B518-088E-4B0F-9170-ED2CA03F9B7A.jpeg B31C74FD-1EA0-4E81-B992-CADB6BCD2AF8.jpeg 0B6F8A1C-9602-4743-9261-754B84B41C60.jpeg BA5A70B7-01EA-4798-80E9-CCA6275815CC.jpeg 54D79AA8-C9FE-4BB5-99DE-13C8EEF277A3.jpeg 52A774F3-6797-4A2F-BB47-CFC8BEA5F5F0.jpeg 6B713262-8530-4541-B5DC-A2D22BCAA48B.jpeg 0D815200-7124-43D9-94C7-D209E51FF887.jpeg
                         
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                        • Kern Dog

                          Kern Dog FBBO Gold Member FBBO Gold Member

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                          I pulled each fuse and there was NO change.
                          I pulled each fuse in the auxiliary fuse panel and also saw no change. I even pulled the plug to the relay that feed the panel, no change.
                          With the stock outer left side headlight plug in place, the purple and red wires show no signs of having power. I probed at the headlight plug and where they were unwrapped near the bulkhead plugs. Nothing there.
                          I pulled the headlight switch plug and grounded the bottom terminal. The lights went off and the doors closed. Once I pulled the probe out, the lights came back on and the doors opened.
                          I'm going to look at the door relay next.
                           
                        • Kern Dog

                          Kern Dog FBBO Gold Member FBBO Gold Member

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                          I did swap in another dimmer switch last night but it didn't make a difference.
                          I just grounded the green terminal and the headlights went out and the doors closed. With a clearer head, these two instances might make sense to me....Both the headlight switch plug and dimmer switch plug have the capability to shut the lights and close the doors.

                          I disconnected the green wires to the headlight door relay. The lights did NOT come on with the key as they have been but they did with the switch.
                          Bad relay?
                          I pulled the relay from the other '70 Charger, Jigsaw.
                          It has a spade terminal where a stud should be. It was obviously replaced some time ago by a non stock part or one for a later Charger.
                          The Jigsaw relay acted the same as my original.
                          Both relays worked the headlights and doors in both cars. Maybe for some reason they don't play well with these aftermarket relays ???

                          I'm going to try this relay idea:

                          1970_Charger_headlight_door_relay_upgrade.JPG
                           
                        • Kern Dog

                          Kern Dog FBBO Gold Member FBBO Gold Member

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                          It was in the last place that I looked.
                          That phrase cracks me up. Of course it was. Once you find it, you quit looking.
                          I think I fixed it.

                          I wired in a Bosch relay and gave it another test.
                          70 relay 3.jpg

                          I put terminal ends on it that allowed me to connect to the factory wiring without cutting the stock stuff. I did this because I didn't have complete confidence that this was going to work.
                          Key on, the headlight doors shut. Okay, good so far. The doors got the signal to close like they should when the headlights are off. NO headlights with the key on. Good again.
                          Ignition on, press switch and the lights come on normally.
                          Ignition off, lights come on, doors don't move.
                          I think it is fixed. I can wrap it all up. Obviously I need to vacuum the carpets again too.
                          I find it odd that the stock relays worked fine with the stock wiring but got all screwy with the relay kit.
                          70 relay 4.jpg
                           
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                          • 1972GY8SE

                            1972GY8SE FBBO Gold Member FBBO Gold Member

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                            Nice job. Stray voltage can be a real bitch to find sometimes.
                            Congratulations.
                             
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                            • 1 Wild R/T

                              1 Wild R/T FBBO Gold Member FBBO Gold Member

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                              Yup, trace voltage was leaking through the relay... Not enough to light the lights but enough to trigger the relays.... Try to keep that circuit breaker in your completed repair..
                               
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