Control Pressure Switch
WARNING: This page is about a different car, the 1990 Cadillac Allante. However, it is still accessible from the selected car via links, so may be relevant.
The control pressure switch monitors boost pressure and signals the EBCM when a pressure of approximately 400 psi (2750 kPa) is reached in the booster servo circuit. This switch is used, along with the booster piston travel switches, to monitor booster operation during brake apply. If an improper brake apply sequence is detected, the EBCM sets a trouble code, disables the anti-lock function and notifies the driver through the CCDIC and/or the BRAKE warning lamp.