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  1. #1
    Sr. Mechanic Ethan's Avatar
    Join Date
    Sep 2009
    Cedar Park, TX

    Default 94's speed gauge jumping and jerking

    So, last night, my speed gauge was jumping about 10 mph in sync with my blinkers, and in general just doing crazy things, and I have no idea why. I'm suspecting the alternator, I've been waiting for it to die, and I tested it this morning, the dash gauge said it was charging around 15 volts with just the engine running, and when I put my multimeter on the alternator, it said 19 volts.

    Could a alternator overcharging cause this problem?

    Or should I look at the speed sensor?
    1994 Chevy Silverado 1500 Ext Cab 350 cuin TBI in dark Chevy blue
    160,000+ miles
    Original paint
    Original interior
    Original engine and tranny
    wrecked twice stolen once
    Diamond Plate bed rails
    Power windows
    Original Alloy wheels
    Original fancy smancy cup holder
    Tow package
    Original plastic bed liner
    K&N Cone Air Intake
    Dual MagnaFlow exhaust(not true dual) with chrome tips
    MSD Street Fire Performance Ignition coil

  2. #2


    its a ground issue, check your ground.

  3. #3
    Sr. Mechanic Ethan's Avatar
    Join Date
    Sep 2009
    Cedar Park, TX


    Which one? There's hundreds of grounds....

  4. #4


    Check all of them! Pay special attention to the grounds for the instrument cluster and the body ground at the battery.
    By the way, if your alternator is making 19 volts, then either it's not grounding properly, or it's a bad regulator. Either way, fix it as soon as possible, because you'll burn up all kinds of stuff.
    Good Luck and God Bless

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