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The reason I am thinking it is mechanical is that I do not have any rear locked indicator (it only turns on when the motor is activated by the rear locker switch, and it keeps blinking), AND the turning radius is horible, the tires are dragging when I go on a tight turn (they squeal)...


It could be that the truck is just stuck in 4wd. If the rear tires turn in opposite directions of each other when the rear is jacked up the rear is NOT locked. There is an indicator that is in the differential. It detects if the actuator has actually engaged the locking mechanism. It feeds the 4wd ecu the info that the RD is locked.

87 Raider 4D56td v5MT1
31's..Basically Stock