9. After you supply air to the trailer, make sure the air lines are not crossed and The trailer brakes are working. This is done by:

Combination Vehiclesmedium

AApplying and releasing the trailer brakes and listening for brake sounds.

BLifting the brake pedal.

CTurning on the parking brakes from the cab.

Detailed Explanation

The correct answer is "Applying and releasing the trailer brakes and listening for brake sounds.". This is based on federal CDL regulations and safety standards.

Correct Answer: Applying and releasing the trailer brakes and listening for brake sounds.

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9. After you supply air to the trailer, make sure the air lines are not crossed and The trailer brakes are working. This is done by:

Detailed Explanation

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