Brake Lockup Madness!

[BruthaMan]

Hey Guys,

Haven't been around much lately as we decided to move from Amarillo down to San Angelo. Been a long move, still not in the home yet.

I was out driving the truck (see signature) to wash it and on the way back to the hotel, the brakes suddenly locked up. I didn't even press on them, just driving along at 25mph and bam...the brakes went to the floor and the truck stopped.

Having never experienced or heard of this before, naturally I did what any dedicated Chevy guy would do, I put her in park and opened the hood. Disconnected the vacuum line to the booster then check, and the brakes came back up. Re-inserted the vacuum and brakes back down to the floor again.

There is plenty of vacuum at the booster line. Could suck the chrome off a trailer hitch.

Did some checking on the forum, but not coming up with anything like this.

Any ideas what happened and/or what I should be looking for? Everything had been fine, no issues at all. Just locked up and will not unlock unless vacuum is off the booster.