Vaccum leak issues - 4x4.....you know the one!

[THEPISTONHEAD]

Is there any diagrams or schematics for the vaccum lines. I got the standard 4x4 defrost issue going on. Havent checked it out yet but looking for more info before I head out the truck!!!! Thanks!

[87mustang]

i don't have the schematic, but you can pressure test everything individually if the vacuum pump works by connecting and disconnecting different things. with the right combination of plumbing, you can verify where the leak is. my problem was the solenoid that turns the front hubs on and off. it was cracked like it got water in it and froze?????? it is located right behind the passenger battery. if that's your problem, it's a dealer only item, and is around 70 bucks.