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Home >> Buick >> 1994 >> Roadmaster Base >> Repair and Diagnosis >> Steering >> Manual Steering >> Steering System - Variable Effort >> Description & Operation

Description & Operation

Variable Effort Steering (VES) system varies the effort required to turn the steering wheel. VES system provides a firmer steering (road) feel and improves directional stability at higher vehicle speeds.

As vehicle speed increases, VES system decreases the amount of pump pressure applied to steering gear assembly. This increases steering effort and improves steering feel. As a safety feature, the VES control module can detect a sudden turn (such as in an evasive maneuver) through input from the steering wheel rotation sensor. The control module then signals the VES actuator, allowing increased pump pressure to the steering gear, thus decreasing steering effort.

VES system consists of a VES control module, VES actuator, steering wheel rotation sensor and Vehicle Speed Sensor (VSS). VES control module receives inputs from steering wheel rotation sensor and vehicle speed sensor (VSS). Based on inputs from these sensors, VES control module cycles VES actuator on and off.

When VES actuator is off (de-energized), full pump pressure is allowed to flow through pump's high pressure line outlet, increasing fluid pressure to the steering gear. See Fig 1 . When VES actuator is on (energized), fluid by-passes pressure line outlet and is routed back into pump, decreasing fluid pressure to the steering gear.

VES SYSTEM ELECTRICAL COMPONENT LOCATIONS

Component Location
Fuse Block Left End Of I. P. (Accessible W/Door Open)
Data Link Connector (DLC) To Right Of Steering Column
Powertrain Control Module (PCM) Below Air Cleaner Assembly
Steering Wheel Rotation Sensor In Engine Compartment, At Base Of Steering Column
VES Actuator At Pump Pressure Line Outlet
VES Control Module (1) To Left Of Steering Column, Above Fuse Block
(1) Module harness connector is Black with 8 terminals.
Fig 1: Variable Effort System (VES) Actuator
G93B40056Courtesy of GENERAL MOTORS CORP.