This bulletin applies to 2013 Chevy Silverado 4WD vehicles equipped with Hydro-Boost. Customers may notice that during full-lock turns or near full-lock turns, the brake pedal may move down or actually self-apply.
This can be caused by the internal dump valve of the hydro-boost not seating properly due to contamination in the steering system. The hydro-boost assembly is not tolerant to certain types of contaminants that may be present in the power steering system.
The hydro-boost is not serviceable and must be replaced. Important note: Before replacement of the hydro-boost, the entire steering system including power steering pump, lines, cooler and gearbox must be flushed to avoid a repeat of the problem.