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94 gmc 2500 brake light on, speedometer not working

Discussion in 'Chevy Trucks' started by BillyRgn, Dec 24, 2012.

  1. BillyRgn

    BillyRgn Senior Member
    Messages: 713

    My 1994 GMC 2500, the HD model with 8 lug wheels. So my brother tells me the other day (vehicles primary driver) tells me when he starts the truck sometimes the emergency brake light stays on even though the brake is off and the speedometer does not work. He said of you shut the truck off wait a minute and restart I usually goes back to normal. So I jump in it today fire it up and the light was on and speedometer off, so I drive it around the block and it was taking forever to shift, it was like holding the gears out reallll long and then shifting hard, it also sounded funny, so I pulled over shut it off, restarted and it was back to normal 100%. The tranny was replaced mid winter of the 10-11 winter. The truck had the main trunk line going to the rear brakes replaced about a month ago. Needless to say the truck is going back to the mechanic wednesday but with the forecast I don't know I I can get it there so I was hoping someone with a similar experence or info could point me in the right direction I'm thinking the speedometer is linked to the tranny somehow and that's what made the shifting weird??? But why would the speedometer not be working and why would it be fine when it restarts?? I'm getting real nervous I'm gonna need it and have it not reset!! Any help is always greatly appreciated
  2. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    My Ford trucks did that it was rear axle's abs sensor that read diff's tone ring gear.

    I am not sure what GM use.
  3. BillyRgn

    BillyRgn Senior Member
    Messages: 713

    Bump I'm sure someone out there knows about the gm please help!!
  4. theholycow

    theholycow PlowSite.com Addict
    Messages: 1,180

    Vehicle speed sensor, mounted in the transmission tail housing.
    Last edited: Dec 26, 2012
  5. TLB

    TLB Senior Member
    Messages: 274

    Most chain auto parts stores will scan your vehicle for trouble codes for free. If you have any in your area you might try that.