78-79 Magnum guages.

1975 - 1979 Mopars

  1. dodge1972

    dodge1972 FBBO Gold Member FBBO Gold Member

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    Plan to install a set of gauges with a tachometer in a non-tachometer dash. Other gauges are also configured differ. My concern is the dash wiring harness. Are the wiring harnesses the same for Magnum with or without the tachometer? I expect to add wiring to the ignition system but I need to consult the wiring diagram to access the Tachometer. Thus the question will the replacement gauges work with the original harness?
     
  2. Pete Kaczmarski

    Pete Kaczmarski Well-Known Member

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    To the best of my memory the wiring harness was the same but it was relatively easy to change to give it a try.
     
  3. soupguy

    soupguy Active Member

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    I just checked my 79 service manual, the harness will be missing the wire for the tach pulse which is position 1 on the cluster connector, its probably the case in 78 too. I do not believe this wire went through the bulk head connector, looks to go though the fire wall some other way to the coil so I wouldn't think it would be hard to add
     
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    • dodge1972

      dodge1972 FBBO Gold Member FBBO Gold Member

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      Checked the backside circuit strips. Appears you are correct. 12 pin connector should read as follows:
      Pin 1 Tech, Pin 2 Temp gauge pin 3 indicator Lamp pins 4 & 5 are the alternator current, Pin 6 indicator lamp, pin 7 fuel, pin 8 oil, pin 9 indicator lamp, pin 10 indicator lamp pin 11 indicator lamp and pin 12 indicator lamp. Please check if this is correct. I can cross check with the original dash pins. Assume the back board land for interconnect is differ for the non-tech version. Thanks
       
    • Micah Pohlman

      Micah Pohlman Well-Known Member

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      The cluster harness is the same but is missing the one wire of the tach signal coming through the bulkhead and the power/ground will need to be added (they might be the same wires for the clock set-up). The printed circuit board is the same for clock and tach clusters. It's a really easy upgrade, basically all you need is a tach head, I've done it many times.
       
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      • dodge1972

        dodge1972 FBBO Gold Member FBBO Gold Member

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        Appreciate your taking the time to respond.
         
      • soupguy

        soupguy Active Member

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        Grabbed these from my 79 service manual hope they help

        IMG_20200611_231709183~2.jpg IMG_20200611_231838931~2.jpg IMG_20200611_231912239~2.jpg
         
        Last edited: Jun 12, 2020
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        • dodge1972

          dodge1972 FBBO Gold Member FBBO Gold Member

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          One set of manuals I need to purchase is the late model b-body books. Again I apricate your taking time to respond to my inquire. Your information confirms the installation. Planning to have my dash recovered, this will provide an opportunity to replace the gauges. I also have an extra set of gauges in storage. I need to check which set I plan to install.
           
        • d9103365

          d9103365 Well-Known Member

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          Following this thread with great interest as I'm trying to do the same thing on my 75 fury sport. I would love to hear any updates! for those interested, the circuit board is indeed different on my car between tach and non-tach dashes. I've also purchased the additional gauges needed, the fascia from a tach car (because the gauge names are different) and also a harness which is available as a reproduction.
           
        • rumblefish360

          rumblefish360 Well-Known Member

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          I did the swap. Plug and play deal.
          (FWIW, looking for a tachometer, speedometer cable)
           
        • d9103365

          d9103365 Well-Known Member

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          Did it really plug right up to the harness? What about the line for the tach pulse that the previous posters mentioned....did you not have to run a new line thru the bulkhead for that?
           
        • d9103365

          d9103365 Well-Known Member

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          BTW, currently my dash only has the "idiot light" for an oil gauge, but with the new tach setup, I'll have to use the REAL gauge, which I purchased....will it hook right up and work properly without anything additional?
           
        • Micah Pohlman

          Micah Pohlman Well-Known Member

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          The extra feed for the tach can be routed though any hole in the fire wall or (what I would suggest) go through the bulk head connector. You'll need a electrical FSM, find the right cavity add a wire to the dash side using the right connector and run that up to the cluster. Adding the engine side wire is easier because you won't have to stand on your head to see what you're doing. If you have idiot lights you'll need to change the oil pressure sending unit to match the gauge.
           
        • dodge1972

          dodge1972 FBBO Gold Member FBBO Gold Member

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          If anyone is interested, I have a set of gauges from a 78 magnum with a tach unit for sale. send PM if interested
           
        • rumblefish360

          rumblefish360 Well-Known Member

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