Odd Brake problem

[tommyddsr]

Brake lines collapsing (small rubber ones) will cause this issue. You are applying great pressure (hydraulic) when applying brakes, but upon release it just bleeds down naturally. So you have enough to engage but not disengage properly.

 

[SteveD]

Tested booster and it is okay.
Pulled ABS fuses and test and put them back in one at a time and no difference.
I will post when I find out.

 

[Chawk]

Just had a similar problem with my '07. Turned out to be front brake lines had corroded. Had the mechanic go ahead and change out the master cylinder, too.

 

[Goofy173]

Like grill ills said, collapsed brake line.

 

[Tim Deater]

The hiss could be the 4x4 system. It uses vacuum to unlock the front hubs, and lack of vacuum to engage the hubs with a spring in the hub. The valve that allows the vacuum or vents it is attached to the brake booster in my 2011. To know if that is it, start the truck, put it in 4high, give it a minute or so then turn the engine off leaving it in 4H. Should not be that hiss as that system would of been vented already.