Functions [4 of 4]
Rear demist
Rear demist (9/2) is activated by pressing the switch on the climate control module (CCM) (3/112). The climate control module (CCM) transmits the data via the Control area network (CAN) to the central electronic module (CEM) (4/56).
The central electronic module (CEM) checks that the conditions to start the demist have been met. If the conditions are met the central electronic module (CEM) activates the relay (2/82) and the heating is supplied with power via the relay.
The central electronic module (CEM) also transmits a request via the Control area network (CAN) back to the climate control module (CCM) to light the LED in the switch.
When the roof is opened on the C70, the rear demist on the rear windshield switches off automatically.
Sunroof operation
The sun roof communicates with the central electronic module (CEM) (4/56) via serial communication. The sun roof has a sun roof module (SRM) (4/33) which manages this communication.
Information about the sun roof position and information to be used for diagnosis is sent from the sun roof to the central electronic module (CEM). The information about the position is transmitted on to other control modules, such as the climate control module (CCM) (3/112) (via central electronic module (CEM)).
The communication between the central electronic module (CEM) and the sun roof mainly consists of diagnostic information.
Rain sensor module (RSM)
The rain sensor module (RSM) (7/149) senses water on the windshield. The rain sensor (RSM) assesses the information based on volume of water on the windscreen and the prevailing exterior light conditions. This information is transmitted via the central electronic module (CEM) (4/56) transmits on to the wiper motor module (WMM) (6/1) using serial communication. The wiper motor module (WMM) in turn ensures that the windscreen wipers are set to the correct speed.
The rain sensor module (RSM) senses if the windscreen is dirty or covered with traffic film and automatically compensates accordingly. The rain sensor module (RSM) also senses heavier splashes on the windscreen. The windscreen wipers are then operated at top speed.
The rain sensor module (RSM) communicate with the central electronic module (CEM) using serial communication. The power supply is from the relay for extended power supply. The relay is checked by the central electronic module (CEM) and is activated when the ignition key is in position I or II. The rain sensor module (RSM) is powered for 3 seconds after the ignition has been switched off.
The steering wheel module (SWM) (3/254) transmits the signal via the control area network (CAN) to the central electronic module (CEM) indicating the position of the windshield wiper stalk and the status of the rain sensor switch. If the rain sensor switch is activated on the wiper stalk (3/134), the central electronic module (CEM) transmits the information to the rain sensor module (RSM) which is activated.
The rain sensor module (RSM) transmits information to the wiper motor module (WMM) via the central electronic module (CEM). The sensitivity can be adjusted using the collar on the wiper stalk.
If a fault occurs in the rain sensor module (RSM), the central electronic module (CEM) transmits an error message to the wiper motor module (WMM). If there is a fault message when the rain sensor module (RSM) is active, the wiper motor module (WMM) selects top speed for the windscreen wipers until the rain sensor is deactivated. If the fault recurs, wiping will only be activated when the wiper stalk is next moved to the single sweep or slow speed position.
Seat belt reminder
The seat belt reminder (10/41) is activated when the central electronic module (4/56) receives a signal from the supplemental restraint system module (SRS) (4/9), via the control area network (CAN), which indicates that the seat belt is not fastened despite someone sitting in the front seat. The three seat belt buckles in the rear seat (3/217-219) have sensors which are directly connected to the central electronic module (CEM). If a belted passenger opens the seat belt while the vehicle is in motion, the central electronic module (CEM) will activate the seatbelt not fastened indicator.
Data is also transmitted to the driver information module (DIM) (5/1) which indicates to the driver that the seat belt is not being used in one of the front seats.
See also Design and Function, Activating automatic start/stop of engine (2010-, only on vehicles with the function automatic start/stop of engine)
Electrical additional heater (certain markets)
Climate control module (CCM) (3/112) checks the function of the electrical additional heater.
The central electronic module (CEM) transmits information regularly to the climate control module (CCM), for example, about the permitted size of the output voltage.
The climate control module (CCM) uses this information to prioritize between its loads. The climate control module (CCM) also uses the information to calculate how much output must be used to activate the electrical additional heater (9/41).
The central electronic module (CEM) (4/56) receives information via the CAN network from the climate control module (CCM).
The central electronic module (CEM) checks that the output voltage is not too great. See: Current limiting
The power consumption of the electrical additional heater is regulated via a pulse-width modulated signal from the central electronic module (CEM).
Tire pressure warning (TPMS)
For more information, see Design and Function, System for Tire pressure monitoring (TPMS).