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Technical Speedo sending unit/ Autometer speedo afu.?

Discussion in 'Traditional Hot Rods' started by AGELE55, Sep 6, 2021.

  1. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    I’m so confused and frustrated right now, I could drive a Kia..
    I have an Autometer speedo that worked great for a few hundred miles, then went spazzo, jumping erratically, then just pegged. I logged like 200 miles getting home from 20 miles away. I checked all wiring and found no issue..hell, it’s only three wires; +12v , ground, and signal. Wires are independent and not routed near other wires, so no inducted voltage. So, I figured the sender failed and bought a new one. Same issue. So then I sent the speedo to Ampmeter for test and check. They say it’s good. I tried recalibrating. One sender does absolutely nothing- zero mph. The other pegs before I get 50 feet.
    Now the fun part.
    My neighbor has the exact same sender not yet installed. I used his meter to ring out the sender for all possible combinations and wrote down all the values. I rang out both my senders and nothing matches between any of the three, but my two are way off from his. Then I notice his sender plug is wired differently? WTF? Both of mine are wired the same, and his is opposite. Check out the photo attached and notice the position of the wire colors.

    Does anybody have one of these they can look at and verify which wiring is correct? Any ideas? I’m getting ready to disassemble the cluster assembly AGAIN and resend the speedo back for yet another test.
    Anyone have a nice reliable Kia they wanna sell? B664F07E-10E4-40A1-BCDA-FAFCF96D220E.jpeg
     
  2. For fear of being too simple... have you checked the actual speedo gear for wear, and that the gear engages each sender at the same depth?
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 50,228

    squirrel
    Member

    Tell us about these independent wires....are they really three wires in one cable housing? or are they three separate wires, going every which way?
     
  4. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    Three wires contained in a common sleeve.
     
    squirrel likes this.

  5. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    Yes. Gear is new and looks great.
     
  6. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    The pic only shows the three wires, but not their arrangement within the plug..

    Pins are labeled 1,2, &3. Which wire to which pin. Can't seem to find a reference.
     
  7. Isn't the plug set up to only fit on the sender one way?
     
  8. GordonC
    Joined: Mar 6, 2006
    Posts: 2,547

    GordonC
    ALLIANCE MEMBER

    I have some new Autometer gauges in the box but can't get at them for about an hour or so. Give me a little bit and I'll check to see whats in there.
     
    AGELE55 likes this.
  9. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    Exactly right. So if the wires are swapped, we have an issue.
     
  10. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    Fingers crossed.
     
  11. Here's a video that might help sort the wiring issue:
     
    AGELE55 likes this.
  12. GordonC
    Joined: Mar 6, 2006
    Posts: 2,547

    GordonC
    ALLIANCE MEMBER

    AGELE5 sorry man my speedo gauge is mechanical. I had forgotten that. My bad.
     
  13. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    Roger that. Thanx anywho..
     
  14. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    SOLVED?

    I’m on it.
     
  15. AGELE55
    Joined: Jan 4, 2018
    Posts: 398

    AGELE55
    Member

    SOLVED?
    I ran the test recommended by pprather above on my two senders.
    One sender failed, showing steady voltage on the sense line (12.5 vdc).
    Second sender passed the test with voltage cycling between close to zero and 12.5 vdc.
    I installed the “good” sender on the tranny and ran my spare wire harness from the sender outside the car and in through the passenger window. I then wired up my speedo in the passenger seat and took a two mile calibration ride per the instructions…again. This time it worked perfectly. I had my phone laying next to the speedo with a speedometer app running and they matched up very closely.
    So, a proven good sender and a new harness worked. I’ll now install the new harness correctly and see what happens.
    Thanks for the support.
    Ps- still mystified by the neighbors harness and sender.
     

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