850i (E31)
The Electronic Steering Column Adjustment with Memory (LSM) system enables the driver to adjust the steering wheel position to suit individual preference, and to enter the chosen position into the seat/mirror memory system. The system also has an exit/entry feature that tilts the column up to ease exit and entry to the driver's seat.
The column is adjustable for length with approximately 40mm of available adjustment, as well as angle, with approximately 4.5 of available adjustment. Adjustment is performed via a lever on the left side of the steering column below the turn signal switch.
Manual Adjustment - The driver may set the column to the position desired by utilizing the adjustment lever on the steering column. Only one direction of adjustment may be performed at one time.
Memory Programming - Once the column has been adjusted to the desired position, the position can be entered into memory via the seat/ mirror programming switch.
1. Ignition switch must be in position 1 or 2.
2. Press the Memory Button (M).
3. Press the desired position switch (1,2, or 3).
Memory Recall - Steering column positions stored in memory can be recalled by pressing and holding the appropriate (1, 2, or 3) seat/mirror position button until the seat reaches its final position. Note: The steering column will not move into position until the driver's door is closed and the ignition key is turned to position 2.
Entry/Exit Feature - To ease entering and exiting the car, the steering column tilts to its highest position when:
- the ignition is switched off.
- the ignition switch is in position 1 and the driver's door is opened.
- the ignition switch is in position 2, the parking brake is applied and the driver's door is opened.
The steering column returns to its previous position when:
- the ignition switch is turned to position 2.
- the ignition switch is in position 2 and either the driver's door is closed or the parking brake is released.
LSM is comprised of:
- Two steering column adjusting motors located on left and right sides of the steering column. The left motor controls column length; the right motor controls tilt. Both motors are equipped with feedback potentiometers for determination of position.
- LSM control unit located behind the center grill above the radio.
- The adjusting switch located on the left side of the steering column below the turn signal switch.
Adjusting motors: Both adjusting motors have a transmission fastened to the forward end of the motors which drive a flex cable attached to a screw drive.
Feedback potentiometers: The potentiometer is mounted on the rearward facing end of the adjusting motors. The control unit can identify the position of the motor by means of the wiper voltage signal.
Initialization of system: In order for the control unit to learn the limits of the system travel, an initialization run of the system must be performed whenever:
- the battery is disconnected.
- the LSM control unit has been disconnected for more than 1 minute.
- an adjusting motor or potentiometer has been replaced.
The initialization run must be performed with the BMW Service Tester or MODIC. The initialization is done by running the adjustments to the physical limit stops and reading the potentiometer voltage. Then, when the system is in normal operation, it stops the travel just prior to the physical limit of travel, to prevent unnecessarily placing stress on the system components and drive parts. For example:
If the initialization run determines that the length adjustment gives potentiometer readings from 4.6 to 0.8 volts, normal system operation will limit the travel to the positions corresponding to 4.5 to 0.9 volts.
The LSM control unit contains an EPROM fault memory. Depending on the type and location of the fault, the system will either switch off completely or switch off the affected function. The stored faults can be read out using the diagnosis module or the MODIC through the diagnostic link. Follow the troubleshooting/testing instructions listed on the screen and in the diagnostic procedures manual. In addition to reading the faults the following can be checked using the diagnostic link:
Status of inputs.
Status of outputs.
Activation of initialization run.
Note: SOMETIMES- you can get them to initialize by holding the button in one position for about 20 seconds then moving it to the opposite position for each direction of travel. I have seen a couple of these columns simply lock up and require replacement also. If you can't get it to initialize manually then it will most likely require dealer intervention for initialization- and to get the fault memory read for potential failed adjustment motor problems.