After connecting the air lines but before backing under the trailer, you should
a) Make sure that the trailer brakes are off
b) Supply air to the trailer system and then pull out the air supply knob
c) Walk around the rig to make sure it is clear
Answer: b) Supply air to the trailer system and then pull out the air supply knob
If the answers is incorrect or not given, you can answer the above question in the comment box. If the answers is incorrect or not given, you can answer the above question in the comment box.