Control Module
The steering wheel module (SWM) has the task of managing the signals for those functions which can be controlled via the steering wheel control stalks and buttons. The signals are transmitted to the relevant control modules via the control area network (CAN). The actual functions are not in the steering wheel module (SWM).
The steering wheel module (SWM) manages the control signals for the following functions:
- Volume control and CD track / radio selection
- Volume control during hands free carphone calls and menu selection for the phone module (PHM)
- Menu selection for traffic information
- Front windshield wipers/washers
- Cruise control
- Turn signal lamps
- High and low beam
- Trip computer and displaying / erasing text messages in the driver information module (DIM).
The control module is integrated in the steering wheel bracket. The steering wheel must be removed to replace the control module. Control stalks, key pads and switches can be replaced as separate units.
Cars with DSTC also have a steering wheel angle sensor installed in the contact reel in the steering wheel module (SWM).
The steering wheel module (SWM) communicates with directly connected components and communicates with other control modules via the Control Area Network (CAN).
The control module checks activations and input and output signals via an integrated diagnostic system. A diagnostic trouble code (DTC) is stored if the control module detects an error. In certain cases the control module replaces the faulty signal with a substitute signal.
Any diagnostic trouble codes (DTCs) are stored in the control module memory. This information can be read off using the appropriate diagnostics tool via the data link connector (DLC) in the car.
A simple way to ensure that the steering wheel module (SWM) is powered and grounded is to flash the headlamp high beam or to change the audio or carphone volume.