Relay T13, located in the optional junction unit under the dashboard B101, receives a supply controlled by the ignition at pin 1 of connector A, along the line protected by fuse F31 located in the junction unit under the dashboard B002; the relay is connected to earth C020 (pin 15) at pin 45 connector B.When the relay coil is energized, the internal contact closes providing a direct battery supply to the heater O040 from the line protected by fuse F45 housed in the optional junction unit under the dashboard B101. The seat heater is activated by pressing the special switch built into the actual seat heater. The heater O040 is connected directly to earth C020 (pin 11) at pin 2.