header bg
8 arrow_forward 0 done arrow_forward 0 done_all

Before you back under a trailer, make sure that

A the trailer brakes are locked.
During coupling, before backing under the trailer, set the trailer air supply control to shut off the air and lock the trailer brakes. On newer vehicles, this control is an eight-sided red knob. You pull it out to shut off the air.
B the air brakes are off.
C the air supply knob is in.