Abstract: A vehicle testing device and method are provided whereby a mechanic can easily test the pneumatic brake systems of a tractor-trailer. The device is used by inputting into the device the electrical and pneumatic outputs of a tractor and by outputting electrical and pneumatic transmissions from the device into a trailer. The device accepts input from a tractor and produces output to a trailer for testing purposes. The testing device is compact and portable and affords a mechanic a convenient tool for efficiently carrying out the necessary safety tests on both the tractor and trailer which may be physically connected or disconnected at the time the testing occurs.

Abstract: A vehicle testing device and method are provided whereby a mechanic can easily test the pneumatic brake system of a tractor, converter dolly and trailer. In addition, electrical circuitry is supplied to allow the mechanic to check the electrical circuits from the tractor to the trailer which supply power for the turn signals, brake lights, clearance lights, auxiliary lights and turn signals. The testing device is compact and portable and affords a mechanic a convenient tool for efficiently carrying out the necessary safety tests on both the tractor and trailer which may be disconnected at the time the testing occurs.