1999 gmc Sierra brake stayed locked

[Jesseyourcalipers]

have a 1999 Sierra 1500 4x4 new body style with diff swapped to have rear disc brakes. Just did the pads couple weeks ago akebono and didn’t bleed just compressed pistons with master cylinder cap off. (Stupid but extreme weather and emergency outing was in rush). This weekend had to slam on brakes for car in front of me cutting me off and truck stayed with brakes locked. I was hitting the gas and trying to pump the brakes trying to move out of intersection and after sitting for a minute it released and back to normal. Fluid level is correct I checked all lines and hoses everything looks fine. Caliper piston boots look good too. Took truck out trying to lock it up again in a gigantic empty parking lot in hopes to see if a caliper was smoking thinking it’s a caliper piston but I could not get it to lock up again. I hit the brakes a few times and have drove it and it’s back to normal. What should I do

 

[zrxkawboy]

Hard to diagnose when it won't repeat, but I'd say there's a good chance the caliper piston stuck.

 

[JavierH19]

That's very odd. Have just over 550k combined on my 03 and 05 gmt800s since new and haven't had that happen to me.

 

[Jesseyourcalipers]

Hard to diagnose when it won't repeat, but I'd say there's a good chance the caliper piston stuck.

is corroded pins possible someone mentioned that but I didn’t think so 🤔

 

[oldhp]

When you have time. I would clean the rear calipers / pistons and put in new seals. One little piece of crud could exactly what you described.

 

[Jesseyourcalipers]

When you have time. I would clean the rear calipers / pistons and put in new seals. One little piece of crud could exactly what you described.

that’s what my dad said hopfully that’s what’s going on

 

[Tomioka]

Replacing the rubber brake hoses would be the first option before fixing/replacing calipers. They go bad internally and can behave as a one-way check valve causing the calipers to lock up.

 

[zrxkawboy]

is corroded pins possible someone mentioned that but I didn’t think so 🤔

I suppose it's possible. Did you check/clean the pins when you had the calipers off?

 

[paulo57509]

have a 1999 Sierra 1500 4x4 new body style with diff swapped to have rear disc brakes. Just did the pads couple weeks ago akebono and didn’t bleed just compressed pistons with master cylinder cap off. (Stupid but extreme weather and emergency outing was in rush). This weekend had to slam on brakes for car in front of me cutting me off and truck stayed with brakes locked. I was hitting the gas and trying to pump the brakes trying to move out of intersection and after sitting for a minute it released and back to normal. Fluid level is correct I checked all lines and hoses everything looks fine. Caliper piston boots look good too. Took truck out trying to lock it up again in a gigantic empty parking lot in hopes to see if a caliper was smoking thinking it’s a caliper piston but I could not get it to lock up again. I hit the brakes a few times and have drove it and it’s back to normal. What should I do

When you swapped the differential to get 4-wheel discs, what that the only thing you changed?

I ask because there was a time when disc/drum systems used a different master cylinder than disc/disc systems. However, other than perhaps bore size, I wouldn't know if this would make difference or cause the problem you're having.

 

[clinebarger]

A GMT800 would have rear disc's from the factory (Except '05-'07 1500 pick-ups) Is this a GMT400?

 

[LouC]

If it has the parking brake shoes that are inside the rear disc make sure they aren’t sticking it adjusted too tight