Dynamic Stability Control (DSC) was first brought to market by BMW, the BMW steering angle sensor provides the DSC (dynamic stability control) with the overall steering wheel angle as measured by the steering angle sensor.
DSC is intended to maintain a vehicle’s intended course when the driver inadvertently over- or under-steers, even on surfaces where some or all of the wheels have different levels of traction.
It does this by combining information from sensors that monitor not only the steering angle, but wheel rotation and the lateral forces exerted on the vehicle by acceleration. The control unit compares this information to an idealized scenario stored in its memory and acts to minimize the differences between the perfect readings and the actual readings.
The steering angle sensor is mounted on the steering shaft and is located at either the bottom of the steering column or behind the airbag in the steering wheel. The later referred to as the switch cluster.
After replacing the steering-angle sensor, it must first be coded and then calibrated. In order to perform its internal calculations, the steering angle sensor requires model-specific data which has to be loaded onto it by means of coding.
Calibration permanently stores the current steering wheel position as the straight-ahead position in the steering angle sensor. In addition, the vehicle identification number is also read from the instrument cluster and stored permanently in the steering angle sensor.
Calibration must always be carried out after the following operations:
- axle adjustments
- After work on the steering column after replacing or programming the active steering control unit
- after replacing or programming the steering column switch cluster (SZL): E60/61/63/64
- after replacing the steering column switch cluster (SZL): E90/91, E87
- after replacing or programming the Dynamic Stability Control (DSC)
- on adjustment of the steering angle sensor
- After replacing the steering box
Active Steering Note:
If the voltage supply of the vehicle was interrupted by disconnecting the battery or deactivating the battery master switch. Below is the procedure for activating the active steering without the BMW diagnosis system.
- Connect the battery or activate the battery master switch
- Start the engine. The following Check Control message appears: active steering inactive
- Move the steering wheel once to the left-hand limit position and once to the right-hand limit position (alternatively, the vehicle can be driven at approx. 30 ‐ 40 kph)
- Switch off the engine, switch off terminal 15
- Start the engine; the active steering is now once again fully functional
The fault memory of the active steering control unit must be deleted, as at least one fault entry is still present. This fault entry is caused by the invalid message regarding the steering angle sensor after the first engine start.
Encoding/programming SZL: E70, E71, E81, E82, E87, E90, E91, E92, E93
Encoding/programming steering column switch cluster: E70, E71, E81, E82, E87, E90, E91, E92, E93
Encoding the steering column switch cluster
Encode steering column switch cluster (SZL) via DSC (from 12/2004). Beginning 12/2004 it is possible to encode the SZL via the DSC. As the SZL does not have its own control unit address, encoding -like the reading of the fault memory- is carried out via the DSC. When the DSC is encoded, the encoding data for the steering column switch cluster is transmitted in the background. During encoding, various parameters are transmitted to check the plausibility of the steering angle in the steering column switch cluster (e.g.: model series, steering-gear ratio, track width).