Steering Mounted Controls Communication Module: Description and Operation
Steering wheel angle sensor
Steering wheel angle sensor is integrated in the SRS-contact reel, which in turn is integrated in the Steering wheel module (SWM).
For Steering wheel module (SWM) with more functionality the steering wheel angle sensor, up to and incl. model year 2007, features a disc with code
A circuit with light-emitting diodes read off the code groove and measures the steering wheel angle during one revolution. The steering wheel angle
sensor also measures the current number of steering wheel revolutions using an analogue magnet-resistive sensor. By comparing the different sensors'
signals, the control module can decide the exact steering wheel angle. Diagnostic trouble code is generated at ± 2.0 revolutions.
From and incl model year 2008 the disc with code groove was replaced with another analogue magnet-resistive sensor. However, the comparison
between sensors takes place in a similar way.
The steering wheel angle sensor gives the Brake control module (BCM) information about the steering wheel speed among other things. Information
about the steering wheel speed is also used by the Electrical power steering module (EPS).
Steering wheel module (SWM) with less functionality is only equipped with the analog magnet-resistive sensor that provides the Electrical power
steering module (EPS) with information about the steering wheel angle speed.
The Electrical power steering module (EPS) uses the information about the steering wheel angle speed to provide the correct pump pressure for the
steering function. As a result, the steering wheel module (SWM) is critical to safety.
It is important that the steering wheel angle sensor is correctly installed and that only Volvo original steering wheels are used.
When replacing the steering wheel, the instructions supplied must be followed to ensure that the 0 position of the steering wheel angle sensor is correctly
Steering wheel buttons
The steering wheel buttons control functions and menu selection for:
traffic information (RTI) (option)
cruise control (option).
The signals from the steering wheel switch left (SWSL) and steering wheel switch right (SWSR) is transmitted via LIN communication.