Ok. I'm helping a girl with her 1998 GMC Sierra truck.

Her brake pedal is extremely stiff, almost too hard to push. She nearly wrecked the other day when the brake pedal randomly did that.

Sounds like the brake booster right?
Are they hard to replace?

My mechanical ability is probably around "medium-low"

THANKS!

 

Sounds like your daignoses is probably right. The booster replacement isn't too bad. The only thing that sucks is that you have to disconnect the operating rod from the brake pedal under the dash so that requires you to be in a contorted upside down position while you take the retaining clip off. You probably won't even have to remove the brake lines from the master cylinder so you won't have to bleed the whole system. I did one on a late 90's Yukon recently and I just took the mounting nuts off and pulled the master out of the way with the lines still attached. Just be sure not to kink them. Also, be absolutely sure you get the brake light switch reattached properly to the pedal (it attached to the same place as the booster operating rod) as the brake switch controls cruise control and transmission torque converter clutch functions.