Steering Wheel and Column Description and Operation

Steering Wheel and Column Description and Operation

Tilt/Telescoping Switch Operation
The tilt/telescoping steering column has a 4-position switch which may be used to adjust the position of the steering wheel in or out which is telescope and up or down which is tilt. The position of the column may be changed as follows:
^ Press the switch up to tilt the column up.
^ Press the switch down to tilt the column down.
^ Press the switch forward and the column moves toward the front of the vehicle.
^ Press the switch rearward and the column moves toward the rear of the vehicle.

The instrument panel module (IPM) receives inputs from the tilt/telescope switch to manually move the column to a desired position. Pressing the control switch sends an input to the IPM. The IPM receives an input and sends a GMLAN message to the driver position module (DPM) which actuates the corresponding column motor.

Motors
Both the tilt and telescoping motors are reversible. For example, the tilt motor moves the column both up and down. When the DPM receives an input to move the column up, the DPM supplies battery positive voltage and ground to the tilt motor in order to move the column up. When the DPM receives a column down input, the DPM supplies battery positive voltage and ground to the same motor, but with a reverse polarity. When the voltage polarity is reversed, the motor runs in the opposite direction and moves the column down.

Position Sensors
Two position sensors are used by the DPM to store column positions in memory and to return the column to the stored memory positions. The DPM provides a 5-volt reference voltage and a ground to both the tilt and telescoping position sensors. The sensor feedback circuit voltage varies from 0.25 - 4.75 volts. Each sensor is mounted to its corresponding motor cable assembly. When the motor rotates its cable, the resistance of the sensor varies. The DPM monitors the feedback voltage to determine the column position via the tilt and telescoping position sensor input circuits. When an entry or exit position is saved, the DPM stores the column positions by recording each position sensor's feedback voltage. When an entry or exit position is commanded, the module moves the motors until all the position sensor feedback voltages equal the feedback voltages stored in memory.

Tilt/Telescoping Memory
Memory settings and the personalization of steering wheel positions are available with the tilt/telescoping steering column. The data stored consists of entry positions and exit positions. The entry position is the position that the steering column moves in when the ignition is turned ON. The exit position is the direction that the steering column moves in when the ignition is turned OFF and the driver door is opened.

An initial memory setting is set in the DPM at the assembly plant. This setting may be changed to suit the customer at the time of purchase or at anytime in the future.

Entry/Exit Personalization
The DPM stores personalization information. The radio is used to enable and disable the personalization feature in the DPM. A GMLAN message is sent to the DPM by the radio which specifies that the DPM enable the personalization feature until disabled again using the DIC.

The steering column control module can store 6 possible positions: 3 entry positions and 3 exit positions.
^ Driver 1 exit position, set using the memory switches
^ Driver 2 exit position, set using the memory switches
^ Default exit position which is all forward, all up, with no memory position set
^ Driver 1 entry position, set using the memory switches
^ Driver 2 entry position, set using the memory switches
^ Last known driver entry position which is when the ignition is turned ON by an unknown driver

Memory Personalization Recall
When a keyless entry transmitter is used to unlock the vehicle doors, the EKM communicates which driver key fob performed that command. The DPM receives the unlock command via a GMLAN message from the EKM.

Tilt/Telescoping Description
The energy absorbing and locking steering column includes 3 important features in addition to the steering function.
1. The steering column is energy absorbing and is designed to compress in a front-end collision which will lessen the chance of injury to the driver.
2. The steering column has a tilt/telescoping control system that consists of a steering column power assembly with positioning motors and sensors, and a steering column control switch.
3. The multi-function lever provides for the control of the headlamp high beams, and the windshield washer and wiper.

Heated Steering Wheel
The heated steering wheel system consists of a heated steering wheel, a heated steering wheel switch, and a steering wheel heat module. The heated steering wheel includes a non-serviceable heating element and temperature sensor. The heating element and sensor are located in the rim of the steering wheel. The heated steering wheel switch is located in the steering wheel switch bezel. The steering wheel heat module is located on the backside of the steering wheel center hub. When the switch is pressed, a signal is sent to the controller and the heated steering wheel is turned ON. The system then remains ON until the customer turns it OFF. The wheels normal operating temperature is 32°C (89.6°F). The wheel takes approximately 3-4 minutes to reach the normal operating temperature. The wheel will take longer to heat up if the vehicle temperature is below -21°C (-5.8°F). The built-in temperature sensor provides input to the controller to limit the temperature to the normal operating temperature. The wheel will not operate if the vehicle temperature is at or above 32°C (89.6°F).