Both front brakes started applying without using the brake pedal. My first problem was at a stop light and the pedal was hard while pressing brakes. like lots of pressure built up. drove a few blocks and let the truck sit for a while and it went away. guessing heat causing brake fluid to expand. tried to come home and got up to 55 mph and it acted like I was pressing the brake harder the faster I tried to go. Had my son bring me car trailer and drug it home. Both front discs have been ground down and can feel a ridge on the outside edge. Back ones not ground down at all.
Work I've done around 10 months ago after my kid was driving and someone pulled out in front of him and he had to slam on the brakes. Pedal went close to floor with little braking power. Rusted brake lines finally blew.
New AC Delco master cylinder
I rebuilt the hydroboost (pirate jack kit)
replaced all the rubber brake lines
replaced all the hard lines. (what a pain in the @$$)
replaced one rear caliper that was dragging
New front rotors
New front & Back pads
Scanner codes. I ignore the mil light because it's usually just a nagging P0406 evap code. Just pulled them and got:
C0265
U1000 (twice)
P0406 (three times)
Not sure if the ABS code would jam on the front brakes?
Haven't messed with the proportioning valve except for new brake lines to it.
Love my Tahoe and it's been very reliable since I fixed the brakes 10 months ago. I've rebuilt the transmission, fixed pump rub in the transfer case, After lots of time on my back, it doesn't even drip on the driveway, Except for a rare drip from the power steering pump. Sometimes steering is tough when turning to lock backing out of driveway. I know this P-steering pump is connected to the hydroboost, but don't think it would lock up the front brakes.
From reading other posts here and on other sites, I haven't tried bleeding when it locks up, or loosening the master cylinder/h-boost connection to relieve pressure. but I'm pretty sure it's a heat thing as it works fine for a little while after cooling down.
Any thoughts? Greatly appreciated
Regards
James
Work I've done around 10 months ago after my kid was driving and someone pulled out in front of him and he had to slam on the brakes. Pedal went close to floor with little braking power. Rusted brake lines finally blew.
New AC Delco master cylinder
I rebuilt the hydroboost (pirate jack kit)
replaced all the rubber brake lines
replaced all the hard lines. (what a pain in the @$$)
replaced one rear caliper that was dragging
New front rotors
New front & Back pads
Scanner codes. I ignore the mil light because it's usually just a nagging P0406 evap code. Just pulled them and got:
C0265
U1000 (twice)
P0406 (three times)
Not sure if the ABS code would jam on the front brakes?
Haven't messed with the proportioning valve except for new brake lines to it.
Love my Tahoe and it's been very reliable since I fixed the brakes 10 months ago. I've rebuilt the transmission, fixed pump rub in the transfer case, After lots of time on my back, it doesn't even drip on the driveway, Except for a rare drip from the power steering pump. Sometimes steering is tough when turning to lock backing out of driveway. I know this P-steering pump is connected to the hydroboost, but don't think it would lock up the front brakes.
From reading other posts here and on other sites, I haven't tried bleeding when it locks up, or loosening the master cylinder/h-boost connection to relieve pressure. but I'm pretty sure it's a heat thing as it works fine for a little while after cooling down.
Any thoughts? Greatly appreciated
Regards
James
May 3, 2026 at 7:02 PM