The relay switch T66, located in the additional fuse box B098, is activated with the key in MAR-ON position (INT/A) - except during starting-, through the line protected by fuse F31 of the Body Computer M001 (pin 27 of connector E).

The output line from relay T66, protected by fuse F55 of B098 (pin 2 of connector A) supplies the seat heating system.

In particular, it is connected to pin 3 of the switches for the driver's heated seat I065 and the passenger heated seat I066 to supply the heating system and to pin 1 of the same switches to supply the built-in LED for backlighting the button.

From pin 2 the switches for heating the seats I065 and I066 are connected to the heater pads in cushions O046 and O047 respectively.

These, in turn, are connected, in series, with the heater pads in the backrests O048 and O049 which are then connected to the optional cab earth C099; pins 4 of switches I065 and I066 are also connected to the reference earth.

Pressing the button on the seat makes it possible to close the circuit and thereby activate the heat and the LED in the switch simultaneously.

The opening of the circuit takes place either by pressing the button on the seat again or through the intervention of the thermal contact integrated in the cushion heating modules.