BMW 7 Series: Electrical Steering Column Adjustment

System Circuit Diagram for Electrical Steering Column Adjustment

Fig. 140: Electrical Steering Column Adjustment System Circuit Diagram

COMPONENTS DESCRIPTION CHART

1. Central gateway module ZGM
2. Front distribution box
3. Distribution box in luggage compartment
4. Steering column switch cluster
5. Steering column adjustment button
6. Footwell module
7. Motor for electrical steering column adjustment, height
8. Motor for electrical steering column adjustment, vertical

K-CAN2 - Body CAN2
FlexRay - FlexRay
KI. 30F - Terminal 30 incorrectly switched

Steering Column Adjustment and Steering Wheel Heating Button

The button for the steering column adjustment can be moved in four directions. It can be used to adjust the steering column upwards and downwards; the distance to the driver can also be adjusted.

The steering column switch cluster evaluates the button status and forwards it to the footwell module. The signal must go across the FlexRay to the central gateway module. From there, the signal is sent on the K-CAN2 to the footwell module. Accordingly, the footwell module activates the motors for steering column adjustment.

The footwell module monitors activation and function.

NOTE: The footwell module is the central control unit for the electrical steering column adjustment. The position of the steering column can be called up or stored in the footwell module for the memory function.

The button for the steering wheel heating is evaluated by the electronics of the steering column switch cluster.

The electronics in the steering column switch cluster send a request across the LIN bus to the steering wheel electronics to switch the steering wheel heating on/off.

The steering wheel electronics switch the steering wheel heating on and monitor its function. The steering wheel heating has an NTC resistor. This resistor is required for temperature control of the steering wheel heating.

Fig. 141: Steering Wheel Heating Button

Fig. 142: Steering Wheel Heating System Circuit Diagram

COMPONENTS DESCRIPTION CHART

1. Steering wheel heating button
2. Steering wheel heating function indicator
3. Steering column switch cluster (SZL)
4. Steering wheel electronics
5. NTC resistor
6. Steering wheel heating
7. Electronics of the steering column switch cluster

KI. 15N - Terminal 15 after-run
KI. 30F - Terminal 30 incorrectly switched
LIN-Bus - Local Interconnect Network bus

Replacing the Steering Column Switch Cluster

Particular care must be taken when replacing the steering column switch cluster or working on the steering column. Comply with the repair instructions.

The coil spring is a very sensitive component of the steering column switch cluster. If sufficient care is not taken when replacing the steering column switch cluster, the coil spring or another component can be destroyed.

A consequence of this can be that the steering column switch cluster only works in part or does not work at all.

NOTE: If e.g. communication with the steering column switch cluster across the FlexRay is disrupted, the junction box electronics switch the windscreen wipers to the emergency mode.

The steering column switch cluster can only be ordered as a complete exchange part. After replacement, the new steering column switch cluster must be adapted to the car.

This involves among other things:

• Initialization of the steering column switch cluster
• Zero-point adjustment of the steering-angle sensor
• Front wheels in the straight-ahead position
• Function test.

NOTE: The transportation lock of the steering column switch cluster is only to be removed after replacement, shortly before fitting the steering wheel.

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