Principles of Operation

Principles of Operation

Steering Column
The steering column is the mechanical linkage between the steering wheel and the steering gear. It houses the steering column switches and is able to tilt to various positions for driver preference. The steering wheel is bolted to the steering column shaft that runs down the center of the steering column. The steering column shaft goes through the dash panel and connects to the steering gear. The steering column shaft connections are made by U-joint type couplings. The steering column shaft is centered by roller ball bearings, which are contained within the steering column.

Power Tilt Steering Column
The power tilt steering column is controlled by an electric motor that is activated by the driver seat module (DSM). The DSM receives input from a rocker-type switch located on the LH side of the steering column just below the multi-function switch. When the power tilt switch is pressed, it sends a signal to the DSM to adjust the steering column up or down. The switch is not serviceable, if a new switch is needed then a new steering column lower shroud must be installed. The power tilt motor is not serviceable, if a new motor is needed then a new steering column must be installed.

Power Tilt Memory Position Programming and Recall
A power tilt steering column position can be stored at any time. The power tilt steering column position is controlled by the DSM. When the DSM receives a signal from 1 of 3 sources (power tilt switch, remote transmitter or a memory position switch) it supplies power and ground to the power tilt motor to move the steering column to the desired position. The DSM also controls the driver seat position, the side-view mirror positions (if equipped) and the adjustable pedal positions (if equipped). For information on the DSM and Memory Position Programming, refer to Seats.

Easy Entry/Easy Exit
The easy exit function moves the steering column to the full upward position when the ignition key is removed from the ignition switch. The DSM receives a key out command over the medium-speed controller area network (MS-CAN) bus and powers the steering column upward. This function will not operate if the steering column is less than the travel distance to the full upward position or the function has been deactivated. The DSM will also cancel this operation if a valid input command is received, such as the power tilt column switch or memory recall request.

The DSM will record the current steering column position before powering the steering column for an easy exit function. This recorded position will be used to return the steering column to this position on the easy entry operation. During easy entry operation, the steering column is returned to the position previous to the easy exit operation. Easy entry operation will be cancelled if a valid input command is received by the DSM.

The easy exit/easy entry feature can be activated or deactivated using a scan tool or via the message center (if equipped). Refer to Information Bus.

Power Tilt Steering Column Hard Stop/Soft Stop
A hard stop occurs when the power tilt column physically reaches the end of travel either up or down and cannot go any further. A soft stop occurs when the power tilt column stops before physically reaching the end of travel. The hard stop is set by steering column design and cannot be changed or adjusted. The soft stop is set by the DSM. To prevent necessary stress on the power tilt column and motor, the DSM will set 2 soft stop positions, one for tilt up and one for tilt down. The DSM will use a preset distance from the hard stop to determine where the soft stop will occur.

The soft stops must be relearned by the DSM whenever a new steering column or DSM is installed. Refer to the Setting the Soft Stop procedure.

Setting the Soft Stop
Use the following procedure to set the soft stops once a new power tilt steering column or a DSM has been installed.

During the setting procedure, one second after the power tilt column reaches the full range of travel either up or down, the DSM will move the column a small amount in the opposite direction that the switch is being pressed. Once the steering column has moved this small amount the soft stop is set and the switch can be released.
1. Turn the ignition key to the ON position.
2. Press the power tilt column switch to the up position.
3. Keep the switch pressed, one second after the column reaches the full range of travel up, it will then move down a small amount. The up soft stop has been set, release the switch.
4. Press the power tilt column switch to the down position.
5. Keep the switch pressed, one second after the column reaches the full range of travel down, it will then move up a small amount. The down soft stop has been set, release the switch.