Vacuum Pump, Brake System

Vacuum Pump, Brake System:

WIRING DIAGRAM

COMPONENT LOCATIONS
342A Main fuse board in the engine bay.
430 Trionic control module
458 Pressure switch, vacuum, in the engine bay on the bulkhead partition.
459 Vacuum pump motor in front of the washer fluid reservoir.
460 Relay, vacuum pump, on the main relay board in the engine bay.

33pin connector
H332 Black connector on bracket below the left-hand A pillar.

grounding Points
G30 Grounding point, left-hand structural member by the battery.


DESCRIPTION OF OPERATION
To improve the strength of the vacuum for the brake servo, a vacuum pump was introduced on certain car models during the latter part of the model year. When engine vacuum is insufficient, pressure switch 458 closes and the coil in relay 460 is supplied with current. The relay operates and motor 459 starts. The vacuum pump runs until the correct level of vacuum is attained, causing the pressure switch to open and the pump to stop.

Grounding of the relay was changed in the interests of better DRIVEABILITY. It is now controlled via the Trionic control module.


FAULT DIAGNOSIS HINTS
1. Check that fuse 4 is intact and supplied with current.
2. Check the performance of the pressure switch.