Vacuum Pump, Brake System

A vacuum pump is incorporated in the brake system on M96 and later Saab 900 cars equipped with a B204L engine and automatic transmission.

The vacuum pump is supplied by a relay controlled from pin 52 of the engine control module via, a pressure switch. The engine control module grounds pin 52 when the ignition switch is in the ON position and the selector lever is moved to any position except P or N.