1989 speed sensor and instrument cluster

Discussion in 'OEM and Custom Interiors' started by 1989k2500, Jan 5, 2020.

  1. 1989k2500

    1989k2500 OBS Enthusiast

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    So the good news is that the sender in the transfer case is good. Gauge still goes out when headlights are on. I found that out after spending $85 bucks on a new sendering unit

    PS I joined this gmt400 forum because that's obviously the type of vehicle I have.
    So im not sure why anyone would think its some carry over square body
     
    Last edited: Jan 11, 2020
  2. 1989k2500

    1989k2500 OBS Enthusiast

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    I don't get why the speedo only goes out when the headlights are on. I put another ground from the back of the cluster to the frame. That didn't help anything.
     
  3. 1989k2500

    1989k2500 OBS Enthusiast

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    I can't believe that with all these teucks out there mine is the only one with these symptoms.
    I would have thought that there are plenty of people not just knowing whats up, but also know how to fix it
     
  4. Mark Gilbert

    Mark Gilbert OBS Enthusiast

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    Talking shit is a great way of getting people to help.

    For someone that can't figure it out on you're own you have a lot of nerve complaining that others can't fix it for you...
     
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  5. Wrench

    Wrench Newbie

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    Just caught the last few posts.

    If your gauge cluster goes whack when you put the headlights on than you've got current crossing overr. That's logical right.

    2 things like would do first.
    Try a different dash cluster. Swap one put with the a buddy for testing purposes.
    If the issue persists unplug the dash lights from the lift switch. Maybe a dash light is shorting on the board.

    Lotta typos. I'm not correcting them.
     
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  6. 1989k2500

    1989k2500 OBS Enthusiast

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    Changing the cluster mught be difficult. They only made them from 89 to 91 with my wiring. I am looking a bit closer at your suggestions
     
  7. evilunclegrimace

    evilunclegrimace Does not always play well with others

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    Unplug the rheostat for the dash lights and see if the Speedo still acts up when you turn on the headlights.
     
  8. 1989k2500

    1989k2500 OBS Enthusiast

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    I think I got it tracked down to the headlight switch and dimmer. Took the dimmer switch apart and cleaned it. The headlight switch had some corrosion going on . Ill replace them both if i have to
     
  9. 1989k2500

    1989k2500 OBS Enthusiast

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    I did a few things yesterday, So I am not sure what did it:
    -removed the solder and desoldered all pin connections on the cluster.
    -ultrasonic cleaned the cluster board
    - disassembled and cleaned the dimmer rheostat
    - disassembled and cleaned the light switch , but then decided to just buy a new one.

    So if you have similar or the same issues with your gauge going out while the headlights are on. then don't right away waste money on a new speed sensor.
    Clean the connections first and replace the dimmer and light switch first.
     
  10. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    Congrats
     
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