[Fiftycamaropgh]

Originally Posted by ctrlz

The steering assist is electric, basically a small motor unit bolted onto the steering rack. Here is description from repair manual. If your unit is locking up at higher speed, but fine at low speed, I think the steering module may not be working right. As mentioned above, the low speed situation is where the unit works hardest mechanically. Good low speed action means it is probably not binding. Sounds like it may be "over stiffening" at higher speed.

The belt driven electronic power steering system consists of the following components:
A belt drive and a ball nut mechanism
A power pack; containing the power steering control module, its sensors, the power steering motor
A torque sensor
The steering gear (rack and pinion)
The belt driven electric power steering system reduces the amount of effort needed to steer the vehicle
by utilizing the power steering control module to control the power steering motor to maneuver the
steering rack. The power steering control module uses input from the torque sensor, motor rotational
sensor, battery voltage circuit and GMLAN serial data circuit to determine the level of motor assist.
Vehicle speed and engine speed from the GMLAN serial data circuit is also used to adjust the amount of
steering assist needed to steer the vehicle. At low speeds more assist is provided for easy turning
during parking maneuvers. At higher speeds less assist is provided for improved road feel and directional
stability
The torque sensor is attached to the steering gear housing near the input shaft, and is critical to proper
operation of the electronic power steering system. As the steering wheel is turned and torque is applied
to the steering shaft, the torque sensor monitors the amount of input torque.
The power steering control module responds to the torque sensor and motor rotational sensor by
commanding current to the power steering motor.
The power steering control module and motor are attached to the base of the steering gear housing, and
applies power assist through the belt drive and ball nut mechanism to the steering rack. The ball nut
mechanism translates the rotational movement of the belt drive system to lateral movement of the
steering rack. The power steering control module has the ability to detect malfunctions within the electric
power steering system. Any malfunction detected that disables steering assist will cause the SERVICE
POWER STEERING message to be displayed on the driver information center. Additionally, the power
steering control module calculates an internal system temperature which is used to protect the power
steering system from damage caused by high temperature. When the calculated temperature exceeds a
pre-determined level the amount of current commanded to the power steering motor is reduced. This will
result in a temporary reduced level of assist. Full assist will return once the calculated temperature drops
below the pre-determined level.

Really appreciate this. So you think the rack is fine, but the steering control module is out of whack? Have you had any software updates performed on your car?