Vacuum lines to operate various components that require vacuum such as the brake booster. This is a pretty big list and finding an efficient method to test all of the joining points plus the accessories that may require a vacuum can be daunting. Efficiency in troubleshooting this issue is important. Symptoms of a Vacuum Leak. High Idle. Rough Idle Locate the pink line that was disconnected in step 2 / image 3, and connect to the Vacuum elbow fitting that we listed at the top of page to the pink line. (see image 6 and 7) Connect the pink line with the new vacuum elbow installed onto the t-fitting the was installed on the boost signal vacuum tee.