Circuit Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
When the brake switch is closed (brake released), the master cylinder pressure sensor signal voltage is low. When the brake switch is open, the master cylinder pressure sensor signal voltage increases.