GM Service Manual Online
For 1990-2009 cars only

The body control module (BCM) or Suspension Control Module, vehicles equipped with RTD, controls an actuator on the power steering pump. The actuator consists of a pintle which moves in and out of an orifice, regulating power steering fluid flow. The control module varies the steering assist by adjusting the current flow through the electronic variable orifice solenoid control circuits. The amount of steering assist is dependent upon vehicle speed and input from the steering handwheel position/speed sensor. As the vehicle speed increases, the steering assist decreases and the driver effort increases. As the vehicle speed decreases, the steering assist increases and the driver effort decreases. The steering handwheel position/speed sensor on vehicles equipped with the RTD system utilizes 2 sensors, in 1 component, and 2 inputs to the control module. The BCM has only 1 input from the steering handwheel position/speed sensor.

For schematics refer to Steering Assist Schematics .