Question What happens if, after connecting a trailer, there is no air pressure in the trailer brakes? Answers The brakes will not work. There will be no air in the cab. The load will not be supported properly. Alternative brakes must be used. Explanation After coupling trailers, be sure to check the air brakes. If air does not flow all the way to the back each brake line, the brakes will not work. This questions appears in the following tests: Georgia Double