Do you know what control unit is in the truck...Curtis maybe?
Does the lift have pothole bars that swing down...possible bad switch there...
On some curtis controllers code 11 has to do with motor shorted....
Check for motor shorted to frame. Disconnect leads from motor. 1 megohm resistance between frame and motor terminal.
Check for controller shorted to B. Disconnect motor leads from controller. 1 megohm resistance between motor terminals on controller and B.
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