Skyhawk L4-121 2.0L VIN 1 TBI (1988)
Vacuum Pump: Description and Operation
Electrical Vacuum Pump
Description
Fig. 1 Electrical vacuum pump
Some GM transverse mounted gasoline engine models are equipped with an external electrical vacuum pump which aids the power brake system at
times of low engine vacuum. The system is comprised of an electric motor, hoses, a controller containing an internal on-off switch and a timer/relay. The
pump is located under the battery in a plastic and metal casing, Fig. 1. Under normal conditions, the system works identical to conventional brake
systems.
Operation
Fig. 2 Vacuum hose routing
