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Vehicle speed sensor

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rh88k5, Nov 8, 2002.

  1. rh88k5

    rh88k5 Registered Member

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    Anyone know where its at (top of tcase on tail?) whats involved in changing it? Is it a dealer only item? I got a trouble code 24, Biggray71 says its a "VSS",like I dont have enough to worry about, I shoulda kept my '69 p/u, nah, I like my blazer, she just needs some tlc. /forums/images/graemlins/k5.gif
     
  2. Stylzz

    Stylzz Registered Member

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    I might not know what I am talking about so get some other advice also. It was my understanding that the VSS is what controls the cruise control. Also, it is mounted on the firewall or somewhere in the engine compartment. I'm kind of curious about where it is and exactly what it does myself.
     
  3. rh88k5

    rh88k5 Registered Member

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    I was thinking on the tranny or t case, I did see a couple of wires running to the top of the tail piece of the t case near the speedo cable, but it was too dark to be sure, I'll check again in the daylight.
     
  4. HarryH3

    HarryH3 1 ton status Author

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    On an '88, the VSS is attached to the speedometer, inside the dash. As the speedo cable spins, it rotates a mirror inside the speedo. The VSS module has an LED that shines onto the mirror and an optical detector that sees the reflected light pulses and coverts them to an electrical signal. It's the auqa colored plastic box on the back of the speedo that has 3 wires going into it. /forums/images/graemlins/cool.gif

    Is the speedo working? If it is disconnected or the speedo cable is broken, you'll get a VSS error code.
     
  5. rh88k5

    rh88k5 Registered Member

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    the speedo is working fine, does the vss have a high failure rate? is there any adjustments to be made after installing the new one? or is it a straight forward replacement?
     
  6. HarryH3

    HarryH3 1 ton status Author

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    The VSS doesn't have a high failure rate that I'm aware of. But before you start buying expensive parts to use as troubleshooting tools, you really should invest in a factory service manual for your specific truck. It will provide troubleshooting flow charts that can save you a lot of cash. It could be something as simple as a loose connector.

    If it turns out that the VSS is bad, you just replace it. There isn't any adjustment required.
     
  7. rh88k5

    rh88k5 Registered Member

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    Factory service manuals, are they dealer items? if not where can I get one?
     
  8. HarryH3

    HarryH3 1 ton status Author

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    See www.helminc.com . You can also find them sometimes on Ebay. /forums/images/graemlins/cool.gif
     

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