Booster Functional Test
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1999 GMC Yukon, 1999 GMC Suburban, 1999 GMC Sierra, 1999 GMC Savana Special, and 1999 GMC Savana Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
With engine off, press brake pedal several times to deplete accumulator reserve. Press and hold brake pedal with about 40 lbs. (18 kg) pressure. Start engine. Brake pedal should fall slightly, then push back against foot. If no action is felt, booster is not operating properly.