They can still check if there are pending codes or codes stored. Seems to me from what your describing there is some sort of electrical fault? But the power steering is belt driven? This is why I asked about stalling out? The only reason for steering to go heavy (not working) is if the engine is not truning over? While the belt is still turning you still have power steering?? Unless you have the navigator? Which has the VAPS system.
Principles of Operation
Variable Assist Power Steering (VAPS)
Navigator vehicles include a VAPS system that controls the level of power assistance available to the driver based on vehicle speed. Below 3.2 km/h (2 mph), full power steering assist is provided to lessen steering efforts and increase maneuverability. Between 3.2 km/h (2 mph) and 191 km/h (119 mph), steering assist will decrease gradually at a calibrated rate to raise steering efforts for increased directional stability and greater road feel. Above 191 km/h (119 mph), steering assist is constant.
The air suspension control module outputs a pulse-width-modulated (PWM) current to the control valve actuator. The control valve actuator controls the hydraulic valve that determines the amount of hydraulic assist provided to the steering gear. The amount of assistance provided varies with the control valve actuator current, which is based on vehicle speed according to a look-up table internal to the module. The module pulse-width modulates the VAPS actuator current to provide the desired amount of assistance. The amount of hydraulic steering assistance provided by the VAPS subsystem is proportional to the average control valve current.
Thursday, December 4th, 2008 AT 9:55 AM