Principles of Operation
Power Adjustable Tilt/Telescope Steering Column
The power adjustable tilt/telescope steering column is controlled by the steering column control switch and 2 electric motors that are powered by the SCCM. The steering column control switch is mounted directly to the SCCM on the LH side of the steering column just below the multifunction switch, but is serviceable separately. The steering column control switch is a 4-position, momentary contact switch. When the steering column control switch is moved to any of the 4 positions, it sends a signal to the SCCM to tilt the steering column up or down or telescope the steering column forward or rearward.
The SCCM continuously monitors the steering column tilt and telescoping motors and circuits for faults. If a fault is detected, the SCCM is capable of setting DTCs.
Tilt/Telescoping Motor Sensors
The SCCM receives digital signals from Hall-effect type rotation sensors that are integral to the tilt and telescoping motors. The SCCM uses these signals to calculate the location of the steering column in relation to the full forward/rearward and full up/down positions. The SCCM also uses these signals to store and recall memory positions, carry out the easy entry/exit operations and to make sure the tilt and telescoping motors do not stall against the steering column end of travel in the forward/rearward or up/down directions. The tilt motor is serviced separately from the steering column. The telescoping motor is not serviceable. If a new telescoping motor is needed, a new steering column must be installed.
Jog Mode
If the SCCM loses the signal from either of the motor sensors, the affected steering column motor operates in jog mode. Jog mode allows limited operation of the affected steering column motor using only the steering column control switch. When the steering column control switch is operated in jog mode, the steering column moves in the desired direction for one second, then stops. The steering column control switch must be released, then pressed again in order to move the steering column for an additional second. Jog mode is an indication that there is a tilt or telescoping motor sensor fault. If the adjustable steering column is operating in jog mode, a DTC may set in the SCCM.
Memory Position Programming and Recall
The SCCM monitors steering column position using Hall-effect sensors that are integral to the tilt and telescoping motors. When a memory position is recalled through either the memory SET switch or the RKE transmitter, the SCCM monitors the Hall-effect sensors and stops sending voltage to the steering column motors once the commanded memory position is reached. If the SCCM receives a steering column switch input during a memory position recall function, the module stops the memory recall and responds to the new steering column switch position input.
When the RKE transmitter is activated, a message is sent over the MS-CAN to the DSM. When the memory SET switch is pressed, the DSM senses continuity to ground on the switch circuit. When the DSM receives either the MS-CAN message or the ground input through the switch circuit, it sends a message over the MS-CAN to the BCM. The BCM acts as a gateway module, relaying the MS-CAN message that was received from the DSM to the SCCM over the High Speed Controller Area Network (HS-CAN). The SCCM then sends voltage over the appropriate circuit to the steering column tilt or telescoping motor to adjust the steering column position.
For additional information on setting and recalling a memory position, refer to the Owner's Literature or Memory Position Programming in Seating .
Easy Entry/Exit
The easy entry/exit function moves the steering column to the full inward and upward position when the selector lever is in the PARK position and the ignition is selected off (if equipped with a push button start system) or if the ignition switch indicates the ignition key has been removed from the ignition lock cylinder (if equipped with an ignition switch). The SCCM receives an ignition status message over the HS-CAN. When the ignition status message indicates the ignition key has been removed from the lock cylinder (vehicles with an ignition switch), the SCCM commands the steering column to the full upward/forward position. For vehicles equipped with a push button start system, this occurs when the ignition status message indicates the ignition has transitioned to off. The SCCM cancels this operation if a valid input is received from the steering column control switch or memory position switch.
The SCCM records the current steering column position before powering the steering column for an easy exit operation. This recorded position returns the steering column to this position on the next easy entry operation. During easy entry operation, the steering column is returned to the position previous to the easy exit operation.
The easy entry/exit feature can be activated or deactivated using the message center. Refer to driver controls in the Owner's Literature for additional instructions for using the message center.