IVR/Instrument Cluster Voltage Limiter on a 65 Dart

Electrical and Ignition

  1. sgrip65

    sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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    Members. Upfront, I have destroyed a few fuel and temp gauges on my 65 Dart instrument cluster. Electronics engineer I am not!!! Any advice on what kind of voltage limiter to purchase and where to buy it, along with a link to a good video or advice on the installation. Thanks. sgrip65.
     
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    • Dana67Dart

      Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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      Define "a few"

      What are your plans? (Stock? Aftermarket custom?)

      How have you destroyed the gauges?
       
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      • sgrip65

        sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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        Thanks. I believe I did as it appears, even with another OEM limiter, I show a pegged temp and a constant 3/4 tank when empty. Apparently, the old Limiter was not functioning. Could be that is the problem....do not know, and that is why I am here with the question. Thanks for the input. Regarding what my plans are, I do not know what to do as I will be using the stock gauges and instrument cluster. Asking for advice. Appreciate your time, and whatever advice you can offer. sgrip65
         
      • 66jim

        66jim Well-Known Member

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        On a few cars I have owned that had bad regulators I hacked into the printed circuit
        board and installed 7805 (5V regulators) on gas,oil and water gauges. I see some
        have used Redline Engineering? has a regulator that better than the 7805 regulators? I am unsure of the maker (Redline) maybe some else can chime in. The 7805 can be purchased at Radio Shack if they are still in business? or on line.
         
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        • RedFish

          RedFish Well-Known Member

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          There is no ground fault protection in a basic 7805 regulator. Without chassis ground it will pass full system voltage through the gauges. The solid state regulator package with some level of fault protection built in comes from real time engineering / RTE.
          There may a fault somewhere. On positive side it can be at the contact pins of your inst' panels circuit board or the purple wire to fuel sender may be shorted to ground out in the engine bay. I'm really just guessing since you didn't fully describe conditions. Do the needles go home at switch off? Temp needle does but fuel needle at 3/4 at all times?
          Proper place to start is buy the good regulator and install it. Add a dedicated ground wire from regulator and metal inst' housing to chassis somewhere.
           
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          • sgrip65

            sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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            Hello Redfish. Thank you much for the information. I did add a dedicated ground to the instrument cluster panel frame. With the ignition on, the temp gauge will, within a minute, peg all the way past the farthest right indicator line. The gas gauge will go empty when the ignition is off, but with the ignition on, it goes to 3/4 full. I will check the purple wire for to ground tomorrow to see if there is a short to ground. I did install a new/repop fuel sending unit, but that does not mean it is working properly. Next step, if I can not resolve this, is to install a new voltage limiter.....do you agree? Thanks again. sgrip65
             
          • RedFish

            RedFish Well-Known Member

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            The limiter is working. Senders and gauges operate on a 80 to 10 ohms range. A zero resistance short to ground is what sends a needle to max and will fry that gauge eventually. Disconnect the temp sender. switch on, if the temp needle moves at all you have a short to ground somewhere.
            I suppose the fault could be the temp sender but most times they fail to open not closed. You could check it with ohms meter.
             
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            • sgrip65

              sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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              Hi Redfish. Thanks for the information. Much appreciated in offering your time and expertise. I will let you, and this thread, in how it goes. Best to you. sgrip65
               
            • Dana67Dart

              Dana67Dart Like a fine wine, only getting better with age! FABO Gold Member

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              There was a recent post about IVR and someone posted a photo of the in fuel gauge IVR. your IVR could be stuck in the closed position supplying 12V to the gauges. do as Redfish said, with the fuel gauge sender (at the tank) disconnected turn key on for a short period of time and see what the fuel gauge does. if it stays at empty I would be looking into the internal IVR in your fuel gauge / resistance in the fuel gauge wiring / sender. the other gauges work the same high numerical resistance ~70-80 ohms or higher = empty, low temp and low oil pressure too. low resistance ~10 ohms should read full, hot and high oil pressure.
               
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              • 66jim

                66jim Well-Known Member

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                Very easy way to test you instrument regulator (if this is your concern). Remove the
                water temp sensor connector (engine bay) put DVM from connector to chassis ground
                should be 5V.
                 
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                • RedFish

                  RedFish Well-Known Member

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                  The mechanical limiter will send higher output during warm up, makes needles move faster to where they are going. Switch on with cold stopped engine, fuel gauge responds, oil and temp don't move. If there is short in temp gauge circuit, limiter senses that and sends all it can. Current takes that path of least resistance. With the minimum of 80 ohms resistance at the fuel sender, and too much current, How would the fuel gauge respond? I don't know that it would go to 3/4 of range but I'll bet my quarter needle would leave home.
                  What I do know... if the temp sender path is shorted to ground, the temp gauge will die eventually.
                  If the limiter sticks closed the gauge with least resistance ( typically the fuel gauge ) will get lions share of the voltage, read way high. The limiter should fail internally but that doesn't always happen. Instead, the copper trace on the circuit board that carries 12 volts to the limiter will burn open as if it were a fusible link.
                   
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                  • sgrip65

                    sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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                    Hello Redfish. All good stuff. I thank you again for the help. Heading out to the shop right now to see what is up using your information.....unless I get caught up with another someone stopping by. Appreciate it. sgrip65
                    Hi 66. I will go out to the shop and check out your direction right now. I will get back to you on this. Thanks. sgrip65
                     
                  • sgrip65

                    sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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                    Hello 66. As instructed, key on, engine NOT running, checking with the VOM from the temp gauge wire to the battery ground, it reads right at 12 volts. Sounds like the limiter is not correct. What say you? Thanks. sgrip65
                     
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                    • 66jim

                      66jim Well-Known Member

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                      Yes the stock mechanical reg. is "stuck" open your getting a full 12V to the gauges.
                      I would not keep testing the gauges they will probably burnout quickly. The mechanical regulator works on the duty cycle principle taking the 12V and pulsing
                      it on/off to get and averaged 5v output, crude but effective for its time like an electric
                      stovetop.
                       
                    • sgrip65

                      sgrip65 66 Dart GT 273, 65 Dart GT 273 HiPo FABO Gold Member

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                      Hello Jim. Thank you for sharing your talent with me in helping to solve this problem. Hope I can help you sometime. Got a bunch of help from many people here on FABO in building this car. It is a great place to be. Thanks again. sgrip65
                       
                    • RedFish

                      RedFish Well-Known Member

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                      All we have to go on is what info is posted. What I read above strongly suggested your inst' panel had the basic standard separate plugged in can type limiter. Now I see a new thread with a picture showing a 3 post fuel gauge. Good luck with it.
                       
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