Vacuum Pump: Description and Operation: Overview

Vacuum pump
To further increase the braking power on the Saab 9-3 Turbo with automatic transmission and the Saab 9-3 Diesel, these cars are fitted with an extra vacuum pump. This extra pump supplies the brake servo with vacuum when the engine is not capable of pumping so sufficiently.
The turbo engine with automatic transmission has an electric or mechanical vacuum pump. The diesel engine has a mechanical vacuum pump.