Temp Gauge Issue

Electrical and Ignition

  1. Collin

    Collin Well-Known Member

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    Having problems with the temperature gauge on the dash working. We have tested the sending unit and found that that is working, we have also tested the wiring to the bulkhead and have continuity, as well as tested the bulk head to the gauge and found that our test light blinks when being applied to the studs of the the gauge. When the sending unit wire was grounded we were able to get the gauge to move, but very slightly. Need help getting this gauge working.....
     
  2. RR383

    RR383 Well-Known Member

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    By what means did you prove the block sending unit working? I'm sort of in the same boat as you on my '70 RR. Big John had some thoughts on troubleshooting. Question, is the engine temp the only gauge in your dash panel not working?
     
  3. Basketcase

    Basketcase Keeper of the Green

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    put a set of manual oil pressure and water temp gauges under the dash (goes with the Day Two look) and never worry if the factory gauges are correct.
     
  4. Big John

    Big John Sit back, relax Don't bitch about the cigar smoke

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    That's probably the gauge. It should have gone to "hot" when grounded. That it's working at all says that the wiring is connected to the gauge, although it is possible that there is bad connection, maybe at the bulkhead connector, that's giving excess resistance to the circuit. I'd check that first. Buy some red Deoxit for the connection (google it) to clean the terminals.
     
  5. Ranger

    Ranger Well-Known Member

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    Yeah, that's what I did. Factory gauge isn't all that accurate anyway (although mine does work and I'm not sure I would stand for it not working).

    [​IMG]
     
    Last edited: Apr 19, 2016
  6. Collin

    Collin Well-Known Member

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    We took an old temp sending unit and put a resistance meter on the stud and another past the threads where it sits in the pump. We heated it and watched the resistance change. We then took the meter and placed one end on the threads of the sending unit in the pump and the other on the stud and watched the resistance change as it heated
     
  7. Big John

    Big John Sit back, relax Don't bitch about the cigar smoke

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    A 10 ohm resistor to ground in place of the sender should make your gauge go to "H".
    23 ohms will put the needle in the center and 74 ohms will be "C"

    All of the stock gauges (fuel, temperature, oil pressure) use this same 10-74 ohm range.
     
  8. Collin

    Collin Well-Known Member

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    Thanks Big John!
     
  9. Collin

    Collin Well-Known Member

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    Took the gauge off, put leads on it and touched the battery. The needle shot up to H immediately. Once re-installed back in the car it stop working. The needle registers right at C but doesn't go any further. Car is running right at 180... Could it be the voltage reducer not working correctly?
     
  10. mac

    mac Well-Known Member

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    the voltage limiter takes battery voltage and reduces it to 5 volts which is then used to supply power to the temp and fuel gauge. if it is the voltage limiter, both the temp and fuel gauge would not operate properly. if it is just the temp gauge and it shows movement with 5 volts and the sending unit shows a change in resistance when heat is applied then there must be a problem in the harness from the sending unit to the gauge or a problem with the pins or circuit board on back of gauge cluster.
     
  11. mac

    mac Well-Known Member

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    IMG_3327_zpso2cyg7gb.jpg
     
  12. stevo

    stevo Well-Known Member

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    this might be a dumb suggestion but....is the sending unit matched with the stock gauge?
    I only ask because I am using an aftermarket oil/temp gauge and I asked a tech if i could run the stock and aftermarket gauges from the same sending unit.
    it was no can do, the sending unit and the gauge are matched.
    just my 02...
    good luck.
     
  13. Collin

    Collin Well-Known Member

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    Mac,

    I took the circuit board off and had all the pins re soldered by a nasa certified solderer. It is a newer sending unit on the water pump
     
  14. Fast Eddie

    Fast Eddie New Member

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  15. dmartin

    dmartin Well-Known Member

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    I don’t trust the idiot gauges get something with numbers more accurate that’s my opinion and I welcome yours
     
  16. Russ69Runner

    Russ69Runner Well-Known Member

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    Always run a set of back up gauges. I don't trust the light by then it is already hot. Find a good location and mount at least the oil and temp gauge. Alt out put or volt meter is good also. Wish they made a set of gauges that mounted in the A pillar type cover. They make them for truck's and every thing else. Oh well keep on wishing.
     
  17. Basketcase

    Basketcase Keeper of the Green

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    when I had my Charger I always ran mechanical gauges. The factory gauges were always way off.
     

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