1. Locate the trailer valve. The trailer valve is typically located on the underside of the semi, near the rear axle. It is a large, round knob that is usually red or blue in color.
2. Turn the trailer valve to the "off" position. This will close the valve and prevent air from flowing to the trailer brakes.
3. Disconnect the air line from the trailer valve. Use a wrench to loosen the nut that holds the air line in place, and then pull the air line off of the valve.
4. Plug the air line. Use a rubber plug or a piece of tape to plug the air line so that air does not leak out.
5. Start the engine and check for air leaks. If you hear any air leaks, tighten the nut on the air line or replace the plug.
6. If there are no air leaks, you have successfully bypassed the trailer valve and your dump truck is now ready to use.
Here are some additional tips for bypassing the trailer valve on a Ford semi:
* Make sure that the semi is parked in a safe location before you begin working.
* Use the proper tools for the job. A wrench and a rubber plug or piece of tape are all that you need to bypass the trailer valve.
* Be careful not to damage the air lines or the trailer valve. If you are not comfortable performing this task, you can take your semi to a qualified mechanic.
