I got a vacuum line on my 2004 Ford F150 that is just hanging loose. Its near the ABS Module thingy on the driver side. There looks to be two, one goes down and over towards the passenger side, and this one seems to just come up and stop right at the ABS module, however its unplugged and I can't figure out where it goes. Does anyone know? My ABS light was on yesterday for a bit, it went off and on, had the codes read and it was something to do with the rear abs sensor malfunctioning, and no network communication, but it hasn't been on since, however my truck is running a tad bit sluggish when accelerating, and I gotta figure its that vacuum line. I just had my phasers done and I assume it must of been knocked loose during the guy working on it.

 

I believe that line is the vent line for your vacuum actuated 4x4 hub down behind your spindle. Crawl under the truck and take a look. Also you should have a matching disconnected line on the other side. They are supposed to be disconnected. (Now im on my phone looking at this and the pictures don't show real good on my phone) but that's more than likely what it is. For more info read the thread that there is a link to in my signature

 

This has suction when the truck is running don't think it's supposed to be disconnected.

 

Oh.........well crawl under the truck. There is a ring behind the steering knuckle that the front half shaft goes through.that ring should have a double vacuum line connected to it that routes up and through the area you are talking about. Make sure that line was not disconnected and left to hang and that is what your seeing. If it was then your front hubs would be engaged and the trucks intake would be constantly sucking in extra air by means of that vacuum line.

I guess you need to track where exactly that disconnected line runs to and to what and where and let us know so we can tell you exactly what its for

 

Sorry I have more. If it is that line I described earlier. Than its the vacuum line that runs you 4x4 system and needs to be connected properly

 

These lines run by the steer knuckle. There is two of them side by side, one like I said runs down and over and the other one was sticking up, but it may of went down to and connected some where, but I can't figure out where. I am utterly confused as to where it goes. It feels like it has suction to it, and like I said my ABS is randomly acting up on me, giving me network communication errors to the rear speed sensor, and I just replaced it yesterday to make sure that wasn't it, and still every once in awhile getting the same random ABS issue. Its got to be related to the vacuum leak.

 

Chris, did you get the answer to your question? I too am having brake trouble and noticed the exact same vacuum line open ended. My front driver's side caliper locks up and doesn't release pressure. The shop replaced the front calipers, pads and hoses. Now they are saying it's contaminated fluid, but I checked and it's fine. I started snooping around and saw the open ended line at the ABS box and wondered if it should be connected somewhere.

 

Yea apparently according to the dealer the line is just a breather.