Terminal 58G from LCM is instrumentation lighting = only button back light.

Terminal 15 = ignition switch pos. 2 activated voltage supply. Comes to pin 5 via unloader relay.

Pin 2 is NTC resistor = temp sensor

Pin 3 is ground (Terminal 31).

The button has semiconductor FET:s to give supply voltage to heater pads. Depending on switch position the supply is cut when set temp is reached.

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E39 530dA -02 M-Sport Messing metallic
E53 X5 3.0dA -06 Sport Stratus grey
E70 X5 40d -12 M-Sport Space grey