Heated seats (certain markets)

Fig 1: Heated Seats Input And Output Signals

Courtesy of VOLVO CARS OF NORTH AMERICA.

The seat heaters are activated by pressing the switch to the right of the climate control module (CCM) (3/112). If the switch is pressed once, they are activated at high temperature. Pressing again will activate low temperature. Pressing a third time switches the heaters off.

The climate control module (CCM) transmits information via the control area network (CAN) to the central electronic module (CEM) (4/56) to activate the seat heaters. The central electronic module (CEM) sends back a signal to the climate control module (CCM) to light the LED in the button. The central electronic module (CEM) compares the signal from the climate control module (CCM) with the programmed value for high/low temperature and transmits a pulsed signal to the control module for the seat heater (9/12-13) about the requested temperature. The number of pulses determines the power at which the control module will operate the seat heater. The control module also compares the value from the thermistor so that it can detect faults in the heater pad.