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Does Temp Gauge Ground To The Case?

Discussion in 'Intermediate CJ-5 and CJ-6 Tech' started by Craig1953, Oct 10, 2018.

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  1. Oct 10, 2018
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
    Joined:
    Feb 5, 2014
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    I just replaced my non-functioning fuel gauge with a new one. The new one is different from the old one in that the new one is "solid state". That it it looks like a small green circuit board with electrical components on it. It seems to work fine. The problem is that now my temp gauge moves slowly up to "H" as soon as I turn the key on, even without the engine running. When I turn the key off it drops back to "C". The temp sender is good. The wire from the temp sender to the gauge is good. The jumper from the fuel gauge to the temp gauge is connected. The cluster case is grounded. Can the new type of fuel gauge have anything to do with the temp gauge malfunction? I have searched here but have not found an answer. Does anyone have any suggestion on why the temp gauge might be malfunctioning?

    Thanks
     
  2. Oct 10, 2018
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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  3. Oct 10, 2018
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Thanks, Howard. That gives me a lead. A post on that link said:

    The power to both gauges is wired in series, so the 12v power comes to the fuel gauge first.
    That fuel gauge then reads the voltage resistance coming from the fuel sender and positions the dial relative to that resistance reading.

    Then one of 2 things happens depending on the age of the gauge.
    If it is an old original style unit the power is reduced inside the fuel gauge down to around 5V and sent via a short wire to the temp gauge, where again the temp sender is supposed to read the resistance and position the marker in the appropriate spot.

    The newer gauges that I am having issues with seem to be direct 12V to both gauges out of the fuel gauge.
    Both the first and second gauges that I have purchased as brand new items have 12V going to the temp gauge via that short wire from the fuel gauge so I presume it is right.

    That is something I am having checked on, but the newer gauges seem to have eliminated the 5v idea.
    But the principle is the same apart from the volt reduction that happens in the older gauges.

    If that is true, then an "old" temp gauge would not work correctly with a "new" fuel gauge because the "new" fuel gauge would be sending 12v to the "old" temp gauge that is supposed to be receiving 5v? Is that correct. If so, then I guess that I would have to get a "new" temp gauge, right?
     
  4. Oct 10, 2018
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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    It's true, but true does not = right.

    The new fuel gauge should reduce the voltage output to the temperature gauge to 5 volts, same as the original.

    And the new temp gauge should not shoot up to "H".

    tThe point to the thread is that there's new production gauges in the supply chain that do nor work correctly, I'd say you've got one of them.
     
  5. Oct 10, 2018
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
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    Doh! You're right. I completely missed the point! I read the prior post to mean that the "new" gauges are supposed to put out 12v and are therefore incompatible with "old" temp gauges. Why do I always just assume that because I buy something new and it doesn't work it's because I'm doing something wrong? Thanks for setting me straight. I will get a replacement fuel gauge!
     
  6. Oct 10, 2018
    PeteL

    PeteL Member Sponsor

    Hills of NH
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    I've said it many times... always suspect the newest thing first.
     
  7. Oct 18, 2018 at 2:35 PM
    Craig1953

    Craig1953 Member

    Santa Barbara, CA
    Joined:
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    Kaiser Willys Auto Supply was real good about sending me a replacement fuel gauge. Unfortunately, the replacement gauge has the same problem. The voltage regulator in the gauge that is supposed to output 5v to the temp gauge is putting out 12v. So if I use it the fuel gauge works, but the temp gauge does not. Mike at Kaiser Willys said that he suspects if he sent me another one it would have the same problem. He refunded my payment and shipping and said the he will contact Omix Ida to see if they have solved the problem, but in the meantime doesn't have one to send me since they are the only supplier. So, although I would like to have a working temp gauge in the cluster, I will install a separate temp gauge.
     
  8. Oct 18, 2018 at 2:47 PM
    Howard Eisenhauer

    Howard Eisenhauer Super Moderator Staff Member Sponsor

    Tantallon, Nova...
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    Check ebay for NOS units, they're on there quite frequently.
     
  9. Oct 18, 2018 at 4:23 PM
    Walt Couch

    Walt Couch sidehill Cordele, Ga. Sponsor

    cordele, Ga.
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    Howard his problem is the 12V from the fuel gauge. The originals dropped it down to 5V to the temp gauge so he needs to drop the fuel gauge output down to 5 volt with an external voltage regulator to the temp gauge right...
     
    Bowbender likes this.

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