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speedo question...how hard

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by NEK5, Mar 1, 2006.

  1. NEK5

    NEK5 3/4 ton status Premium Member

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    ok my speedo is starting to **** the bed....at night only half of the pointer lights up and none of the warning or status lights if that is what you would call them like the service engine or 4x4 engaged.i think it might be the printed circuit in the back because when my freinds dad checked the bulbs he said he saw the service engine light a couple of times....and sometimes when it was real cold when i left work at night for some strange reason it would light up like half way but it hasnt done that in a long time..could this be the printed circuit?

    if not do they make a speedo with an odometer and the service engine lights??? if so how hard would it be to put it in....but i would rather fix the one i have because i dont know what u do about the miles
     
  2. hack500

    hack500 1/2 ton status

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    probably some bad connections with the PCA (Printed Circuit Assembly) or bad bulbs... if it is just the printed circuit I believe that you can buy new ones from chevyduty or LMC, and re-use your current guages.

    how did your friend's father check the bulbs - by taking the guage cluster apart? or?
     
  3. NEK5

    NEK5 3/4 ton status Premium Member

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    he took them out and hooked them out to something else with some power wire...i think i might the PCA and or the dakota digital set up
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Just pull your cluster and figure out whats wrong.

    You'll see if the printed circuit board is bad, but from your post, it sounds like a simple power supply or ground issue. The '90-91 (electric speedo) clusters power and ground everything through essentially two wires, while the earlier clusters used a much more "standalone" method of powering each component. (gauges, lights, etc) So it only takes one of those two wires being less than perfect to affect everything in the cluster.

    You'll have to pull it one way or the other, you might be able to save yourself some money though.

    Nothing on these clusters is "failure" prone, but with age, connections come loose or get dirty.
     
  5. NEK5

    NEK5 3/4 ton status Premium Member

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    could that be the cause of sometimes the service engine or 4x4 engaged lights dont work?
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Absolutely. EVERYTHING on that cluster is run off of the one instrument panel connector in the back.

    Of course, as with everything, there can be MANY causes of the problems you are talking about, if this is a basket case: The 4wd light switch could be bad, the wiring from the ECM to the cluster could be bad, the ECM could be bad, etc. Half the lights working is odd though...your year cluster feeds all the bulbs and grounds them all through the same connector pin(s)...

    Likelihood of those problems all at the same time is very small though, so more than likely you are dealing with a connector issue. At least you can hope for that. :) With as many problems as you are experiencing with the cluster, it's likely going to be pretty obvious once you pull the cluster out what the issue really is.

    The connection on the back of the cluster is pretty weak, although probably fine if never messed with...the printed circuit board simply has the copper ends glued to the plastic of the PCB where the hard plastic instrument panel connector plugs in...those copper ends can simply peel up and slide to the side, losing contact.
     
    Last edited: Mar 5, 2006
  7. NEK5

    NEK5 3/4 ton status Premium Member

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    well before i got my blazer it was involved in an accident/minor fire so that stuff may have been touched...they have worked so i`m assuming loose connections is the problem
     

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