Instrument cluster voltage regulator, on a 1970 Plymouth Valiant, 340 Duster

Discussion in 'Electrical and Ignition' started by DaveM, Dec 2, 2018.

  1. DaveM

    DaveM Active Member

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    Hello where is it located on a 1970 Plymouth Valiant, 340 Duster ?
    It is not on the back side of my instrument panel.
    Is it inside the panel or on the firewall, under the dash?
    My temp & fuel gauge read zero...
    I would like to check the IVR if I could locate it!
    Any help or pics would help and be appreciated.
    Thanks in advance
     
  2. 4spdragtop

    4spdragtop FABO Gold Member FABO Gold Member

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    I believe its inside the fuel gauge.
     
  3. DaveM

    DaveM Active Member

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    Thanks so I have to remove the whole printed circuit board from the instrument panel to get to the regulator inside?
     
    Last edited: Dec 2, 2018
  4. Dubob

    Dubob Well-Known Member

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    If it’s a rally dash it is part of the fuel gauge. It is not serviceable. I converted my Demon to a solid state regulator.
     
  5. DaveM

    DaveM Active Member

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    how did you convert, instructions available?able to use your orig fuel gauge/s ? thanks in advance.
     
  6. Dubob

    Dubob Well-Known Member

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    Last edited: Dec 2, 2018
  7. 4spdragtop

    4spdragtop FABO Gold Member FABO Gold Member

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    Dubob has it nailed. The gauge itself has to come out of dash/bezel to work on it. Quite a few steps involved to get to that point.
    Good luck.
     
  8. DaveM

    DaveM Active Member

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    thank you. but do you think my limiter is bad if my oil pressure gauge works? Both temp & fuel gauge do not work...
     
  9. DaveM

    DaveM Active Member

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    thank you but since the limiter supplies voltage to the three gauges and only the fuel and temp do not work, do you think its defective/my prob?
     
  10. Dubob

    Dubob Well-Known Member

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    It’s not too hateful. Take your time. But what I don’t understand is if it’s bad the oil pressure won’t work either. You could check to see if you’re getting approximately five volts at the sending units for temp etc. it could be pins loose on printed circuit board or even bad traces etc on the board. Also could need better grounding of the instrument cluster housing.

    Sorry We were typing at same time. If one gauge is working the limitor is operating. Maybe the temp sender is bad, can check with and ohm meter. The fuel could be the sender or the grounding to the tank isn’t good.
     
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    • 4spdragtop

      4spdragtop FABO Gold Member FABO Gold Member

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      To fix it, the gauges/cluster has to come out. Before that, check oil sender and connections to diagnose.
      Once gauges are out, you can do a newfie check on them with a 6v lantern battery.
      Fuel gauge gotta be fixed anyway right?
       
    • DaveM

      DaveM Active Member

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      If you are sure the oil press gauge is fed off of it then I will troubleshoot the items you mention. thanks again for your time and support. I will update when I find the smoking gun. thanks again
       
    • 4spdragtop

      4spdragtop FABO Gold Member FABO Gold Member

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      Get a factory manual.
       
    • Dubob

      Dubob Well-Known Member

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      Without a doubt the temp and fuel, oil all get their power from the limiter. 12 volts come into the fuel gauge thru the limiter and changes to 5 volts approximately, then thru the windings for fuel gauge out to sender, then thru temp and oil out to its sending unit. Keep in mind the voltage will be a pulsing voltage as the regulator contacts open and close. All the sending units provide a variable resistance to ground. If you check the general section here there should be downloadable manuals if you don’t have one.

      Something else is you could go right to the sending units and see if you have that voltage at the wire. Would help isolate it.

      InkedIMG_0034_LI.jpg
       
      Last edited: Dec 3, 2018
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      • toolmanmike

        toolmanmike FABO Staff Staff Member FABO Gold Member

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        Thread moved to electrical forum.
         
      • jimjimjimmy

        jimjimjimmy lobsterman FABO Gold Member

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        only the temp and fuel are powered thru the limiter the oil pressure is not .
         
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        • 4spdragtop

          4spdragtop FABO Gold Member FABO Gold Member

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          I was thinking that but wasnt sure JJJ.
          Thanks.
           
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          • RedFish

            RedFish Well-Known Member

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            Rally or not, All thermal gauges operate on a 5 volts. A single limiter/regulator supplies 5 volts to 2 or 3 thermal gauges. Warning lamps operate on 12 volts. If one OEM thermal gauge works, the limiter/regulator is working. Fault at other gauge(s) has to be some other problem, gauge, sender, connections.
             
          • 67Dart273

            67Dart273 Well-Known Member

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            No, only the amp gauge is not associated with the limiter. The other three are. The fuel gauge has a 3rd post which is the 5V output and feeds to the oil/ temp gauges. See Red's post above^^

            In fact you can see it in the photo posted, marked 5V

            inkedimg_0034_li-jpg.jpg
             
          • 67Dart273

            67Dart273 Well-Known Member

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            If you thrash around the www there is a procedure to feed an external 5V regulator or IVR into the fuel gauge 5V stud and do away with the internal / OEM one
             
          • jimjimjimmy

            jimjimjimmy lobsterman FABO Gold Member

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            my apologies to everyone you are right the last thing I want to do is spread bad info .
             
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            • 4spdragtop

              4spdragtop FABO Gold Member FABO Gold Member

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              Thanks for clarifying guys.