Heated Steering Wheel Module (HSWM)
The steering wheel heating function is controlled by the Climate Control Module (CCM) (4/6), Central Electronic Module (CEM) (4/56), Steering Wheel Module (SWM) (3/130), Heated Steering Wheel Module (HSWM) (4/148) and Infotainment Control Module (ICM) (3/281). Upon activation via the switch on the Climate Control Module (CCM), the indicator on the switch illuminates and a request is sent to the Central Electronic Module (CEM). The Central Electronic Module (CEM) then powers the Heated Steering Wheel Module (HSWM) via a relay, and regulation begins.
The temperature is regulated by a thermistor in the steering wheel (NTC resistor) giving the SWM regular analogue information about the steering wheel's current temperature. The temperature is sent via A dedicated LIN-bus to the HSWM, which regulates the heating element in the steering wheel using PWM supply.
When the engine has been started, steering wheel heating is always deactivated initially if automatic activation of steering wheel heating is not selected (setting in the Infotainment Control Module (ICM)). Automatic activation of steering wheel heating does not occur if the passenger compartment temperature is above + 30 °C.
The temperature may be experienced as somewhat irregular above the steering wheel because of the material's thermal conductivity, but this is normal.