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help...no speedo/odometer

Discussion in 'Chevy C/K Truck Forum' started by braspu, Jun 17, 2009.

  1. braspu

    braspu New Member

    I am having a problem that is driving me nuts. I have a 91 Chevy k1500, 350, 700r4. Neither the Speedo, odometer, nor cruise controls are working. I changed out the inst. cluster and the vss. It does not have a mechanical speed sensor, electric magnetic. I originally thought it was the cluster so I changed that, no good. A few weeks later the service engine light came on, checked for codes and got 24. I than changed the vss. Still nothing. I checked the harness to the vss with a multi meter while the key was in the on position and got a reading from it. Any suggestions or ideas are appreciated.

    thanks,
    Brandon
  2. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    You probably have a bad DRAC module. The DRAC is located behind the glove box. This is what converts the analog signal to a digital signal.
  3. 5speedsilverado

    5speedsilverado New Member 1000 Posts 100 Posts

    what were the codes? and did you fix them?
  4. m.gauthier

    m.gauthier New Member

    Sooo. Im having the same problem right now. What is this DRAC module? I have no idea what im lookin for
  5. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    The early trucks had a DRAC Module which is the speedometer buffer. Later, the DRAC was incorporated into the PCM. What year is your truck? Have you thought about including your truck info into your signature?
  6. m.gauthier

    m.gauthier New Member

    Its an 89 gmc C1500
    350 V8 5.7L
  7. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    I believe 1992 was the first year GM used a DRAC in the trucks. The 89 still used a speedo cable and the vss sensor was located in the speedo head. The 2 wires from the vss went directly to the PCM. To change the ratio on an 89 a reduction box was used on the speedometer cable at the trans or transfer case.
  8. m.gauthier

    m.gauthier New Member


    VSS is located in the transmission. I changed it ,but im still not getting any signal to my speedometer/odometer gauge. And my cruise isnt working. So its gotta be some wiring somewhere is faulty. Just dont know where. Multimeter check? Where at? whats the reading supposed to be in which locations?

    Also. Where is the VSS buffer? Apparently the speedo wired run into a buffer according to the haynes manual. Know where its at?
  9. Jimmiee

    Jimmiee New Member 1000 Posts 100 Posts

    So you are saying you have a VSS sensor on the trans and no speedo cable?
  10. m.gauthier

    m.gauthier New Member

    yah its electrical. I changed the VSS thinking that was it. But that didnt work. Im still getting the 24 code

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