I have a 1990 B2600i, 4x4. We had a really cold spell the last couple of days and my truck has been sitting for a while. I started it up the other day and the Anit-Lock indicator came on. It's been on ever since, and the pedal goes almost all the way to the floor. I didn't think to check at first, but my brake fluid was below the Min mark. So I added some, but the Anti-Lock symbol is still on. I don't know if the brake booster froze because the fluid was low and it got so cold. I can't find any leaks anywhere so I can't imagine where it went. I bought the truck used, but someone had done some kind of brake work on it because it has some mods to the brake lines in the back. The lines to the LSGV (Load Sensing G-Valve) in the back are corroded and broken. So I think they bypassed it.

Basically, I'm looking for a head's up where I should start looking for trouble. I have new brakes in front and rear and a buddy who manages a brake shop adjusted the E-brake cable so everything was set properly.

 

I'd bleed the entire system first.