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  1. #1

    Default 1989 TopKick Differential Lock

    I have an 89 GMC TopKick that is a line truck, single axle. There is a differential lock light and a buzzer that is on and will not go off. I don't have any manuals for the truck part of my rig. Can anyone tell me how to get the light/buzzer to go off or how to unlock the differential. I've looked everywhere and can't find a button, knob, or switch that has anything to do with this issue.

  2. #2


    What manufacturer is he diff. can you see the part number on the switch? Try this pdf for answers
    Last edited by Coach24; 02-14-2012 at 06:58 PM.
    2010 Chevy Silverado Z71 ext cab.4x4
    72 Monte Carlo 350-415 hp- sold (June 2011) to pay medical bills
    79 Impala 350 4bbl 375 hp- sold (June 2011)to pay medical bills

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