The lock and unlock lines that connect to the switch travel back out of the door and then in to the interior of the car to provide vacuum to those two branches of the system, depending on the position of the switch.

You can reconnect the solid yellow line to the center of the switch at this time.

From this point on this guide will focus on testing the lock side of the system since this was the side that showed the leak when testing the main line under the hood. All of these techniques can be applied to the unlock side if you have a leak there.

Plug the end of the lock line that is inside the door.

Retrieve your vacuum pump from under the hood to use it inside your car on the next step.