Brake pedal locks up downhill

[USMC93]

Hey there. I have a 2014 GMC Sierra and 99% of the time my brakes work fine.

 

however I realized sometimes in stop and go traffic down hill or times when I’m on flat ground and I’m at a stop with my brake pedal pushed in then release and try to push it again the pedal will lock up and not go all the way down and my truck will be slow to stop again. Granted this only happens at 5mph or so in traffic but I still feel my truck should not do this it’s pretty scary when I’m stopped and let off to move up a few feet and then feel like I can’t stop.

 

if anyone knows the cause please help.

 

Thank you

[Sierra Dan]

Sounds like your Vacuum Pump may be failing or has failed.

Sometimes it can send metal shavings into the engine, as the pump is lubricated by engine oil.

Are you out of warranty?

 

https://www.gm-trucks.com/forums/topic/212773-vacuum-pump-replacementdiagnosis/

[qwank]

Vacuum pump for sure