GM Service Manual Online
For 1990-2009 cars only
Figure 1:

Brake Warning System


Object Number: 1883281  Size: FS
Master Electrical Component List
Brake Warning System Description and Operation
Control Module References
Hill Hold Valve (HP7)
Figure 2:

Hill Hold Valve (HP7)


Object Number: 2000223  Size: FS
Master Electrical Component List
Control Module References
Brake Pressure and Vacuum Sensors (HP7)
Hydraulic Brake System Schematics