Practice question

What is the purpose of the 7-pin electrical trailer cord (jumper cable) connecting tractor and trailer?

To power the trailer's tail lights, brake lights, turn signals, clearance marker lamps, and anti-lock brake system (ABS)
To carry the service braking signal that applies the trailer brakes
To supply compressed air to the trailer suspension
To transmit the trailer's load weight reading to the cab

Answer: A — To power the trailer's tail lights, brake lights, turn signals, clearance marker lamps, and anti-lock brake system (ABS)

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