Description & Operation

Variable Effort Steering (VES) system, or Electronic Variable Orifice (EVO) steering system, varies the effort required by driver to turn the steering wheel. Both VES and EVO provide a firmer steering (road) feel and improved directional stability as vehicle speed increases.

System decreases amount of pump pressure applied to the steering gear as vehicle speed increases. Reduced pump pressure increases steering effort, improving steering feel.

System consists of an EVO control module, EVO actuator and Vehicle Speed Sensor (VSS) buffer. EVO control module cycles EVO actuator on and off based on input from VSS buffer. When EVO actuator is off (de-energized), full pump pressure is allowed to flow through pressure line outlet, increasing pump pressure to the steering gear. When EVO actuator is on (energized), fluid bypasses pressure line outlet and is routed back into pump, decreasing pump pressure to the steering gear. Electronic Climate Control (ECC) panel displays EVO system faults upon request.