1989 TopKick Differential Lock

Discussion in 'Medium-duty Truck Forum' started by bugvert, Jan 25, 2012.

  1. bugvert

    bugvert New Member

    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. Coach24

    Coach24 Rockstar 3 Years 5000 Posts

    Last edited: Feb 14, 2012

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