Guage testing and adjustments

Electrical and Ignition

  1. Dana67Dart

    Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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    As some of you know I fried my temp gauge when my mechanical IVR lost the heater wire full volting the temp and fuel gauge.

    It still functions, but normal operating temp is just at the low tick of the temp gauge, normally it would be 1/4 past the low tick.

    (Note: the temp gauge is 67 so the normal range is shifted to the right)

    Luckly the fuel gauge functions as expected.

    EDIT--
    I have been collecting clusters to gather good working gauges. So far I have I really good used, 2 less than great but functional, and I lucked in on a NOS temp gauge.

    To date I have 4 clusters and one NOS Temp gauge.

    all 4 clusters have snap on speedo cables so none of them are 67.

    2 of them have the shifted temp "normal" ranges. I don't know what year the shifted "Normal" became centered.

    End EDIT----


    I have another cluster inbound and it looks promising.

    I figured I would test the used gauge assuming the NOS gauge is the most accurate.

    I set up a series of 100w resisters and a series of 18 awg jumper cables.

    I can do any resistance from 1 ohm to 100 ohms.

    I have a 12v power supply and an rt-eng.com IVR4 limiter.

    I set up the gauges and resisters etc.

    Actual resistance values below, the input voltage to the IVR was 13.66v
    1. 10.4 ohms
    2. 17.3 ohms
    3. 18.3 ohms
    4. 23.4 ohms
    5. 73.5 ohms

    10 ohms NOS
    PXL_20220520_001016198.jpg


    10 ohms Used
    PXL_20220520_001229617.jpg

    23 ohms NOS
    PXL_20220519_233437179.jpg


    23 ohms used
    PXL_20220519_233718982.jpg

    73 ohms NOS
    PXL_20220520_001723961.jpg


    73 ohms used
    PXL_20220520_002018313.jpg

    NOS no voltage (cold, 5 minutes)
    PXL_20220520_001427826.jpg


    Used no voltage (cold, 5 minutes)
    PXL_20220520_001806022.jpg



    Here is the interesting thing...

    23 ohms has been the defacto 1/2 gauge resistance value. As you can see the 23 ohm readings were around 1/3 reading.

    17 to 18 ohm caused half gauge reading

    18 ohms NOS
    PXL_20220520_000143344.jpg

    18 ohms used
    PXL_20220520_000403709.jpg

    My conclusion is the used gauge is about as accurate as it can be.

    I had messed with the upper and lower limits in the past and had no idea where it should read.

    I started with adjusting the high limit and got it on the line when 10 ohms was applied.

    Then I adjusted the low limit and got the needle on the line with 73 ohms

    I then went back and forth, high and low, adjusting one affected the other till I got a happy medium.

    Now both gauges read about the same.

    It will be interesting to see how the incoming cluster works out.

    Either way I have 2 options to replace my bad gauge.
     
    Last edited: May 21, 2022
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    • CFD244

      CFD244 These pretzels are making me thirsty. FABO Gold Member

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      Thanks for the testing and results. Good info here.:thumbsup:
       
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      • Dana67Dart

        Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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        There will be a few ohms additional resistance from the wire in the car, 55 year old connections and the like.
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        A few ohms in wire is not going to affect much, unless there is "a few more" ohms at the connections---the sender (and don't forget ground, fuel), the kick panel connector (fuel gauge), the bulkhead connector (oil and temp) the cluster harness connector --including possible bad PC board pins, the IVR CONTACT FINGERS IN THE CLUSTER (solder jumpers across), and the nut connectors at the gauges to the PC board.

        Also don't forget cluster ground, which must be "same as battery"
         
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        • 67Dart273

          67Dart273 FABO Gold Member FABO Gold Member

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          • Dana67Dart

            Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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            I'll be happy to do some testing on it if you send me one.:rolleyes:


            My fuel sender is OEM and reads really accurite. I need to lower the pickup to get the last 2 gallons
             
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            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              I received the Cluster I was expecting Thursday. Here is the results of those gauge tests.

              What I found interesting is both of these gauges were 1/2 way at 23 Ohms where the NOS and the other gauge was 18 at 1/2 way.

              Maybe the proper way to calibrate these gauges is to make them accurate at 1/2 scale by shifting the needle that direction with proper voltage and resistance applied by making the high and low readings wider and shifted?


              Below tests were done with the same set up as the first post.


              Temp Gauge no power
              PXL_20220520_222635838.jpg

              73 Ohms (Temp)
              PXL_20220520_222727750.jpg
              23 ohms (Temp)
              PXL_20220520_222846028.jpg

              18 ohms (temp)

              PXL_20220520_222956880.jpg

              10 ohms (temp)
              PXL_20220520_223141147.jpg


              No Power Fuel
              PXL_20220520_222642110.jpg

              73 ohms (fuel)
              PXL_20220520_223315275.jpg

              23 ohms (fuel)
              PXL_20220520_223515729.jpg

              18 oms (fuel)
              PXL_20220520_223700435.jpg


              10 ohms (fuel)

              PXL_20220520_224046616.jpg
               
              Last edited: May 21, 2022
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              just for grins I did 9 ohms on the fuel gauge

              PXL_20220520_224213667.jpg
               
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              Here are some photos of the misc. gauges I have collected. Note the faceplate part numbers and the back of the gauges. some are the same some are different PXL_20220521_212325263.jpg PXL_20220521_212342134.jpg

              another

              PXL_20220521_212404599.jpg PXL_20220521_212415991.jpg


              Another

              PXL_20220521_212509413.jpg

              Note the holes on the back of this gauge are reversed from the previous two PXL_20220521_212600026.jpg

              Another
              Centered Temp "Normal" range (NOS gauge)

              NOTE:
              The photos in my first post show a shifted "Normal" face plate on the loose NOS gauge and a center "Normal" on the Used loose gage. Prior to testing I swapped the face plates between the two as I expected to use the NOS gauge in my dash and needed the shifted "normal"

              In the photos below I used the photo of the correct face plate for the NOS and the correct faceplate for the used gauge.

              I know, just trying to keep you all on your toes!


              PXL_20220521_212611758.jpg PXL_20220521_212629965.jpg
               
              Last edited: May 21, 2022
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              PXL_20220521_212713273.jpg PXL_20220521_212725240.jpg PXL_20220521_212853959.jpg PXL_20220521_212905087.jpg PXL_20220521_212915908.jpg

              The gauges the loose face plates are off of

              Note the white plastic insulator and this one must have been off of another car or earlier year as the needle is different shape and color PXL_20220521_213028434.jpg PXL_20220521_213039469.jpg

              Another

              Note the white plastic insulator and this one the heater wire came off of the left stud PXL_20220521_213054127.jpg PXL_20220521_213103437.jpg
               
              Last edited: May 21, 2022
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              This one had a black insulator that was cracked and fell apart when I took it out of the cluster, :( the rest of the gauge looked great.

              I'm still trying to figure out why some of the adjustment holes are on the left while others are on the right. My first thought was one side was fuel and the other side was temp, but I don't know. might just be later years or different manufacturer.

              PXL_20220521_213501725.jpg PXL_20220521_213519983.jpg

              more photos
              (I marked this one Temp, but I don't know for sure)
              PXL_20220521_213144154.jpg PXL_20220521_213153631.jpg

              Another

              (I marked it Fuel but I don'tt know for sure)
              PXL_20220521_213213232.jpg PXL_20220521_213223162.jpg
               
              Last edited: May 21, 2022
            • Dana67Dart

              Dana67Dart The parts you don't add don't cause you no trouble FABO Gold Member

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              Matt sent me this chart he found.
              might explain the 18ohm centers on some of the gauges I have.


              Mtester_datacs.jpg



              All of the gauges I have are from this type of cluster, I don't know what year they changed it.

              upload_2022-5-21_16-47-26.png
               
              Last edited: May 21, 2022
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