Stiff brake pedal which ratchets to floor

[bigkylewhite]

Sorry if this has been addressed recently but couldn't find anything on a search. '97 Suburban diesel with ABS. At low speed stops (and only at low speed stops), brake pedal starts very stiff and 'ratchets' down to where it finally brakes free. The pedal goes down to where it should and the burb lurches to a stop. Everything moves freely - no metal bind. Calipers/pads/rotors are fine. Feels like an ABS issue. Light is on intermittently but it will do this regardless of whether the light is on or off. Any thoughts?

[Tinman238]

I believe your diesel Suburban has hydro-boost for brake assist instead of vacuum assist. If so, the brake pedal is assisted with hydraulic pressure from the power steering pump. When you say it happens at low speeds only, that's when your engine (and power steering pump) are spinning the slowest. If the pump. or associated system, has a pressure issue, that could be the problem. Does it happen at idle?

[SLJ2137694]

To me it sounds like a false ABS activation. Pull a fuse on the ABS system to deactivate it and try a stop. If the problem goes away you probably have an ABS wheel sensor or wiring issue. If the ABS light has been on you probably have a code stored that should give you a head start on a fix.

[j cAT]

Originally Posted by SLJ2137694

To me it sounds like a false ABS activation. Pull a fuse on the ABS system to deactivate it and try a stop. If the problem goes away you probably have an ABS wheel sensor or wiring issue. If the ABS light has been on you probably have a code stored that should give you a head start on a fix.

if the ABS light comes on when making a normal non slide stop at slow speed , this is abs problem usually, as stated , the front sensors that have been pushed out by rust or bearing failure contaminating the sensor face........