One problem related to power assist hydraulic brake has been reported for the 2006 GMC Sierra 2500. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 GMC Sierra 2500 based on all problems reported for the 2006 Sierra 2500.
Sudden and complete failure of brakes and steering. Started vehicle, placed in reverse, unable to stop or steer. No emergency assist from accumulator, manual brakes only. Vehicle was placed in neutral, then stopped with e-brakes and service brakes. Power steering reservoir overflowing, puddle on garage floor of fluid, fluid gushed when cap removed. Vehicle towed to dealer where it operated normally! dealer unable to diagnose at time of this writing. Similar complaint from relative with the exact same vehicle, had same thing happen 4 times. Hydro-boost system on a diesel 2500 hd.