97' 4x4 4.6 144k owned 3 years now. Have a brake problem. Does not feel like I'm getting full vacume boost. Brake pedal high and rear brakes adjusted properly. Pulled booster check valve and it worked fine. Went ahead and cleaned check valve and vacume line to manifold just in case. Tested brakes while check valve pulled and braking worse - so appears I have some boost, just not enough. Also, my ABS has never worked on this truck. I'm figuring their somehow related. Any help is appreciated. Poured over the forums and got the check valve idea, but my Chiltons book is no help on this one. thanks

 

Booster itself could be dying. Without the boost, you will need alot of extra leg strength for pedal pressure.

 

Forgot to say that truck is not throwing any errors. Will a truck throw an error for low boost pressure? Can the booster be tested? Is it possible that it is something else?

 

I have never seen a code for boost problems. As for testing, there are vacuum pressure testers out there, just need to find what the in and outs should be so you have something to compare to. Check you loal autoparts store. They usually have testers and/or meters that you can "rent" to check your truck out. Or they may just do it for you right there.