Steering Column Operation

Power for the steering column operation is supplied via a megafuse in the Battery Junction Box (BJB) to the Central Junction Box (CJB). The CJB in turn supplies power to the column adjustment motor, the reach and tilt solenoids and also the adjustment potentiometers in response to driver requests made with the column adjustment switch.

The steering column adjustment switch is a joystick type, 2-axis switch with positions for reach and tilt adjustment. The switch can also be rotated to change the mode selection from auto to manual. The switch is hardwired to the CJB with 3 wires. The 3 wires provide a power supply to the switch and the mode select switch, the third connection is a ground provided by the CJB. Up/down (tilt) and in/out (reach) selections on the switch are each passed through a resistor of differing values to the CJB. The CJB monitors the output value from the switch and operates the column adjustment motor in the required direction and simultaneously energizes the required solenoid for tilt or reach adjustment. When the applicable solenoid is energized, a clutch is engaged and locates on a lead screw. The motor rotates the lead screw and the rotational drive of the screw is transferred into linear movement of the applicable clutch to move either the tilt or reach adjustment. For reach adjustment, the lead screw drives the outer housing in or out as required. For tilt adjustment the lead screw drives a tilt lever which moves the column up or down as required.

The position of the column is monitored by potentiometers which are connected to the CJB. The CJB monitors the output signal from the potentiometers to precisely control the positioning of the column in each plane.

The CJB controls the memory positioning of the column via a Medium Speed (MS) Controller Area Network (CAN) body system bus connection to the Driver Seat Module (DSM). The CJB receives information regarding the particular remote handset used to enter the vehicle and outputs positional information relative to that stored for the handset. This information is used by the CJB to move the column to the memorized position relating to the remote handset used.

The column logic in the CJB also incorporates an entry/exit mode. When the vehicle is unlocked or the ignition is switched off, the CJB lifts the column upwards to its maximum tilt position to allow the driver more room below the steering wheel and improve access/egress of the vehicle. When the ignition is next switched on the column will adjust to its previous position.

The electric steering column lock is controlled by the CJB and is an integral function of the passive start system.

Refer to: Anti-Theft - Passive (Description and Operation).