53 Turn Indicator Bulbs (in dash) Both Flash - NCRS Discussion Boards

53 Turn Indicator Bulbs (in dash) Both Flash

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  • Gary C.
    Administrator
    • October 1, 1982
    • 17648

    53 Turn Indicator Bulbs (in dash) Both Flash

    Friend has a 53 - both turn indicator bulbs in the speedometer house flash when turn signal lever is on left turn or right turn.

    Checked ground bar ground and it's OK. Flasher was replaced.

    Suggestions appreciated. Thanks,

    Gary
    ....
    NCRS Texas Chapter
    https://www.ncrstexas.org/

    https://www.facebook.com/profile.php?id=61565408483631
  • Philip P.
    Expired
    • February 28, 2011
    • 558

    #2
    Re: 53 Turn Indicator Bulbs (in dash) Both Flash

    What do the front and rear lights do? More than likely the switch from looking at the wiring diagram. Did anyone do any rewiring that may also be a clue.
    My thoughts anyway.
    Phil

    Comment

    • Gary C.
      Administrator
      • October 1, 1982
      • 17648

      #3
      Re: 53 Turn Indicator Bulbs (in dash) Both Flash

      Phil,

      Lights all seem to work ok. L & R turn, brake and park.

      Before I got involved the wiring harnesses, turn cancel switch, etc. were replaced

      Only both dash tun indicator bulbs flash dimly.

      Safety pinned the two turn indicator bulb wires and checked grounds OK.

      Am now trying to trace the voltage to the two turn signal indicator bulbs.

      Suggestions appreciated. Thanks,

      Gary
      ....
      NCRS Texas Chapter
      https://www.ncrstexas.org/

      https://www.facebook.com/profile.php?id=61565408483631

      Comment

      • Richard M.
        Super Moderator
        • August 31, 1988
        • 11323

        #4
        Re: 53 Turn Indicator Bulbs (in dash) Both Flash

        Gary, I've never worked on a '53, but I just looked at the '54 schematics. Some thoughts............

        I see on the '54 schematic, and I'm assuming same for '53 hopefully, the 2 dash lights are fed from Dark Blue(Left) and Light Blue(Right). These go to the Park Lights(edit-I should have said "front" directional lights"). But the "common" for these dash indicator bulbs come from a common Black wire which goes to the flasher. They don't go to "hard" chassis ground. If that Black wire is open to the other bulb, or to the flasher, maybe it's getting a floating ground through the filament of the other bulb and lighting both up. Maybe check for continuity on those black wires to both bulbs and flasher. Schematic looks like Terminal "P" on the flasher.

        Or........It may have something to do with the Stop Light circuit. If a directional is on, and you step on the brake, that directional should still flash. The feed for the stop lights comes from the light switch, then to the stop light switch, then passes through the directional switch. The dir switch then feeds the flasher if dir's are on, or bypasses it to the stop lights:Puple(Right) & Pink(Left). When Lt or Rt directional is on, and you step on the brake, does either Lt or Rt dash light go out? What about the Stop lights? Do they react properly? I see connectors between the dir switch and harness. All ok there?


        1954Schematic

        Rich

        Comment

        • Gary C.
          Administrator
          • October 1, 1982
          • 17648

          #5
          Re: 53 Turn Indicator Bulbs (in dash) Both Flash

          Rich,

          This is really a strange one to me as I've never worked on a 53-4 6 volt 3 prong flasher system.

          Quick summary - jumpered 6 volt and grounds everywhere directly to the battery to bypass the wiring harness. Still no joy.

          Resolved by adding a ground to both the "P" terminal of the flasher and the flasher case itself.

          On the schematic, the flasher "P" terminal is a black wire that runs to the L & R turn signal indicator lamps in the speedometer.

          One of the first things I did after making several resistance to ground checks, was to run a direct grounds to the turn signal lamps. But that didn't fix it. Was really scratching my head on this one.

          Appreciate the help. Thanks,

          Gary
          ....
          NCRS Texas Chapter
          https://www.ncrstexas.org/

          https://www.facebook.com/profile.php?id=61565408483631

          Comment

          • Philip P.
            Expired
            • February 28, 2011
            • 558

            #6
            Re: 53 Turn Indicator Bulbs (in dash) Both Flash

            Gary if the wiring was replaced one of the leads for one of the turn signal indicator may be switched, if the lamps are dim it really sounds like it is feeding back from one of the other lamps in the circuit. It appears the wiring for the indicators and the front lights come from a common point the switch. I would check the wiring to the dash lamps and see if one is not some how connected wrong, one power side to the ground.
            Phil

            Comment

            • Richard M.
              Super Moderator
              • August 31, 1988
              • 11323

              #7
              Re: 53 Turn Indicator Bulbs (in dash) Both Flash

              Gary, Glad you got it!

              So after reading how you solved it, I checked online for a LPX 3 terminal flasher. "X" is input power from the Pink Ign wire, "L" is Load to the outboard directional lights, and "P" is for Panel lights. I did read on another forum that the case of the flasher needs to connect to chassis ground. Strange that the schematic doesn't show that. Is the flasher clipped into some sort of housing? I wonder if that housing/holder is supposed to have a separate ground wire attached to it?

              My guess is that if "X" has +6V, and when "L" see a load(i.e. a directional lights up), then internally the flasher relay switches the flasher case ground to the "P" terminal to supply ground to light the dash indicators sequentially with the outboard directionals.

              I wonder if you remove the ground from the "P" terminal, but keep the case grounded, would the Dash lights will still work correctly?

              Rich

              Comment

              • Gary C.
                Administrator
                • October 1, 1982
                • 17648

                #8
                Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                Phil and Rich,

                Phil - turn signal dash lights are basically on their own circuits with the front/rear turn signal lights and not tied into the other dash lights.

                Rich - that was my thought that the case grounded to the "P" terminal. But it didn't work that way. The dash buss bar ground checked good. Don't know about the flasher bracket to ground as I didn't personally see that, but was told it grounded out good as well.

                Your guess on how the flasher worked is same as mine. Looked for a schematic of a 3 prong flasher, but didn't find on.

                To me it was interesting that the ST12 wiring drawing doesn't show the flasher case to ground since we had to add a ground to make it work.

                Very confusing and frustrating to say the least. Didn't make sense, but it worked.

                Thanks for y'al's help! Best,

                Gary
                ....
                NCRS Texas Chapter
                https://www.ncrstexas.org/

                https://www.facebook.com/profile.php?id=61565408483631

                Comment

                • Philip P.
                  Expired
                  • February 28, 2011
                  • 558

                  #9
                  Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                  THis may not be the same but is similar in design interesting problem one for the memory .
                  Phil140108_wiring_diagram.jpg

                  Comment

                  • Chris S.
                    Extremely Frequent Poster
                    • January 1, 2000
                    • 1067

                    #10
                    Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                    the flasher is mounted to the metal ground strip via a clutch head bolt that goes thru the clip that holds the flasher.
                    1954 Corvette #3803 - Top Flight 2012, Bloomington Gold 2012,
                    Triple Diamond Award 2012, Gold Concourse Award 2012, Regional and National Top Flight 2014
                    1954 Corvette #3666 - "The Blue Devil" - Pennant Blue - restoration started
                    1957 Corvette - FI 3 sp - Black and Silver

                    Comment

                    • Gary C.
                      Administrator
                      • October 1, 1982
                      • 17648

                      #11
                      Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                      Thanks Chris, figured it ought to be grounded.

                      Phil, that's how I thought it should be - grounded on the center post, but it wasn't.

                      Thanks,

                      Gary
                      ....
                      NCRS Texas Chapter
                      https://www.ncrstexas.org/

                      https://www.facebook.com/profile.php?id=61565408483631

                      Comment

                      • Philip P.
                        Expired
                        • February 28, 2011
                        • 558

                        #12
                        Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                        Gary
                        Great to know you solved the problem. Interesting way that they do the flasher in a 53. Grounds are so critical in these cars that would be one that is easily missed. I looked at the ST-12 and the ground for the display lamps is connected to the P terminal, which must be ground in the flasher, the diagram I was looking at previously only showed the 2 connections. It now makes sense that the exterior lights worked with the dash lamps being dim. Attached is part of the wiring diagram in the ST-12.
                        Phil

                        53-54 flasher.jpg

                        Comment

                        • Richard M.
                          Super Moderator
                          • August 31, 1988
                          • 11323

                          #13
                          Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                          Guys, I was poking around and found this schematic of the 3 terminal flasher. A Tung-Sol 535 is a functionally correct 6v flasher for 53 & 54. It looks like the schematic below except it's 6 volt not 12 volt. I'm a bit confused about the P terminal. It would have 6V on it when the flasher is activated. Grounding P would cause a power to ground short, correct?

                          Why they designed the dash lamp grounds to be driven from the P terminal is still a mystery to me. I understand that they didn't want to run the dash lights from the Load terminal because it would affect the flash rate on the outboard lights, so they isolated them using the P terminal.

                          180794d1279316899-4-wire-flasher-conversion-3-term-ts-flasher.gif

                          #535 Flasher
                          535.JPG

                          Comment

                          • Eric F.
                            Expired
                            • June 30, 2003
                            • 319

                            #14
                            Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                            I'm currently experiencing the same problem so I thought I'd share my discoveries to update this thread.

                            There is a definite difference between the original Tung Sol 229 flasher (commonly referred to as a 535 flasher) and the modern 535 flasher available today. I took them apart to try and resolve my problem and to satisfy my curiosity. The modern 535 flasher (they are available from various suppliers but all have the same generic markings) contain a transistor whereas the original and "old school" flashers didn't contain any solid state components. I believe that is the reason the modern flashers require the "P" terminal to be grounded. I'm still in the investigation process and will share the results for others encountering the same problem in the future.

                            Originally posted by Richard Mozzetta (13499)
                            Why they designed the dash lamp grounds to be driven from the P terminal is still a mystery to me. I understand that they didn't want to run the dash lights from the Load terminal because it would affect the flash rate on the outboard lights, so they isolated them using the P terminal.
                            It was mystery to me too until I discovered the "P" terminal and the "L" terminal alternate between being active. Thus, the dash indicator lamps and the exterior turn signal lamps alternate between flashing. Still not sure why an electrical engineer of the day designed it this way; maybe it has something to do with 6 volts systems.

                            Comment

                            • Richard M.
                              Super Moderator
                              • August 31, 1988
                              • 11323

                              #15
                              Re: 53 Turn Indicator Bulbs (in dash) Both Flash

                              Interesting info Eric.....Did you also have to ground the case?

                              I had to re-read the entire thread to figure out what we were talking about.

                              Comment

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