speedometer quits and Service Engine light comes on.

Discussion in 'Chevy Truck Forum' started by The Tall Guy, Mar 16, 2010.

  1. The Tall Guy

    The Tall Guy Member

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    #1 The Tall Guy, Mar 16, 2010
    Last edited: Mar 16, 2010
    Hello, I've got a 1988 Chevy Silverado. It runs fine and all the guages work. When I drive, the speedometer starts out working fine, then sometime in the trip the speedometer quits and shortly after the Service Engine light comes on. I pulled a code 24 "vehicle speed (vss) sensor circuit fault". Can I test the sensor in the transmission or do I have to take it off? Or do I just replace? Does transmission fluid come out when you take the vss off? Thankyou.
     
  2. Bob D

    Bob D Senior Member

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    Need to have rear wheels turning to measure voltage (AC).
    Frequency is proportional to vehicle speed.
    Along with output to the speedo, it's output is used by the PCM to control various engine and tranny functions (on later years; unsure of '88).
    Replacement for 2WD is about $25 - $30.
     
  3. The Tall Guy

    The Tall Guy Member

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    Will transmission fluid come out when I take the vss off?
     
  4. Bob D

    Bob D Senior Member

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    No.
    May want to check the elec. connection first (make sure it's not severely corroded / getting good contact) before purchasing replacement.
    There is an O-ring that seals the unit.
     
  5. The Tall Guy

    The Tall Guy Member

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    If I check the elec. connection and there is corrosion or not good contact, do i remove and replace the connector? And if so, do I splice a new connector on to the wires?
     
  6. Bob D

    Bob D Senior Member

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    I would just disconnect the connection and spray / clean the contacts (IF they are all crudded up). Verify that bad connection is not cause of fault before you spend $ on new VSS.

    PS: Welcome to the forum.
     
  7. The Tall Guy

    The Tall Guy Member

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    I cleaned the contacts and I replaced the vss. I cleared the code and took it for a drive. At about 5 miles the speedometer quit. Then about 2-3 miles further, the engine light came on. I checked the code and it was a #24 again. Any other Ideas of what to do?
     
  8. leolkfrm

    leolkfrm Full Member

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    change the speed sensor
     

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