'65 Formula S Tachometer Help?

Discussion in 'Electrical and Ignition' started by dibbons, Mar 13, 2018.

  1. dibbons

    dibbons Well-Known Member

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    I can't find anything in the 1965 Plymouth Factory Service Manual (in the electrical section) regarding the factory installed tachometer. I would like to know which bulb is used to light the face, and what the wiring setup is, any help would be appreciated. Thank you.
     
  2. 4spdragtop

    4spdragtop FABO Gold Member FABO Gold Member

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    • dibbons

      dibbons Well-Known Member

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      I found a magnifying glass and was able to read the installed (burned out, of course) bulb on the socket of an orange wire: #57. I will assume that is what the factory specified. It looks like wire colors for the tach gauge hook up are yellow (hard to say) (with a female/rubber push on connector) and black (with a round circular brass terminal). Still need to find out which wire goes where.
       
    • Big_John

      Big_John In my defense, I was left unsupervised.

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      Page 8-107 in the FSM gives you the wiring.
       
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      • dibbons

        dibbons Well-Known Member

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        Got it, that page fooled me by listing it as for Models AR-1 and AR-2 (Belvedere and Satellite).
         
      • Big_John

        Big_John In my defense, I was left unsupervised.

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        Yea, it's same wiring colors across the board. I probably should have mentioned that. LOL.

        If you go in the back of the FSM, there's all the specs. Page 17 and 18 gives you the bulbs.
         
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        • valiantwagonguy

          valiantwagonguy Well-Known Member

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          Here is a visual the cut (yellow,red,and black go to the cut wires in the harness and it all just plugs together

          IMG_3678.JPG

          IMG_3682.JPG

          IMG_3684.JPG
           
        • RedFish

          RedFish Well-Known Member

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          If you took one of these OEM tachs apart you would find a piece of fiber board with 2 studs mounted in it. It could be dropped through the housing one of two ways. That's why the housing wasn't marked which is which. Notice the 2 studs are different lengths. The shorter is sender/signal.
           
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          • dibbons

            dibbons Well-Known Member

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            The two studs on the back/rear of my tach are exactly the same length. However, they are different colors. Looking at the back of the tach, with the lamp at the 12 o'clock position, the stud on the left is brass colored and the stud on the right is steel colored.

            The stud on the left also has a flat round washer on it colored brown. At first I thought it was a fiber type insulating type washer, but now I'm not sure because it actually feels like it is metal.

            The stud on the right had no washer. Now I remember removing it and the tab for the wire connection, of course, was between the nut and the body of the tach, so I suppose a washer is not needed there. Unless, of course, it fell off sometime in the last 50 years.

            I do have the update circuit board that is sold to repair/update the operation of the tach (still in the box somewhere, I will be searching for it). It will be exciting to bring this tach back to life.