4Goffs

I have a 2011 Grand Cherokee Limited 4x4 with 47k miles.

When trying to stop i can hear hissing in the cab & my brake pedal gets real stiff.....Now i spoke with my mechanic & he told me it sounds like the brake booster but when i took it to him with the part for repair the brakes started working fine. The computer also gave no codes during the 30 minutes of driving it was hooked up. The brakes also didnt malfuction as they were the previous 2 days before.
To make matters worse i drove to work today after doing all the tests last night & the brakes are getting stiff/hissing again.

I live in Ohio & its been cold so it seem that this issue only comes up in the morning when i leave for work & in the evening when i go home.

Has anyone heard of this issue? Again the Jeep is not throwing a code & the issue only happens when its cold. I need to fix this before i need to make an emergency stop & cant due to whatever the heck is going on.....this is ...

Firestorm500

You've got a bad diaphragm in your brake booster.

You still have brakes, but reduced or no power assist.

Change out the booster.

cruiser54

You don't get codes for EVERYTHING, you know.

cloudedjudgment

LMAO!!! That's exactly what I was thinking.

4Goffs

Ah.... Haha.... I am not a mechanic or anything close but thanks for pointing that out.