Description & Operation

Based on vehicle speed, Variable Effort Steering (VES) system, or Two-Flow Electronic (TFE) steering system, controls amount of power steering pump pressure applied to steering gear.

At speeds of about 20 MPH or less, pump pressure is increased, resulting in easier turning of the steering wheel. At speeds of about 20 MPH or more, pump pressure is decreased, resulting in more difficult turning of the steering wheel. This increased steering effort at greater speeds provides a firmer steering (road) feel.

The VES system consists of a Multi-Function Chime (MFC) module, Powertrain Control Module (PCM) and TFE actuator (or electronic variable orifice actuator). PCM receives a signal from the vehicle speed sensor. Based on this signal, PCM provides a ground for vehicle speed sensor circuit of MFC. Pump pressure is increased when MFC grounds the TFE actuator under the following conditions:

• Vehicle speed is 0-20 MPH and is increasing.
• Vehicle speed is less than 17 MPH and is decreasing.
• Vehicle is not moving. (If vehicle does not move within 2 minutes, however, MFC removes ground from TFE actuator).