This is what I found out. :dance:
The IMS Guardian switch is actually a seat heater switch with 3 built in LEDs. The orange cable on the IMS connector on terminal 3 is supposed to be connected to 58d circuit which is a circuit with GY/BU/RD wires. 58d is the positive lead of the instrument cluster illumination. This can be found at the intermittent windshield wiper potentiometer (for example). This is necessary if you want the 3rd internal (actually almost invisible) LED to light up when the instrument cluster is lit and dimmable.
Most other switches in the dash use a GY/BU/BN wire which is 31d the negative lead of the instrument cluster illumination. This is normally used on the dash switches (PSM, Central Lock, Rear Heat Defogger, Convertible Top) because the switches switch positive power and not ground as it is the case on the seat heater switch.
This said, it is not necessary ore useful to connect the orange wire to pin 1 of any other switch in the area as explained in the IMS Guardian instructions.
Pin 1 is always an intermittent switched and normally open circuit. Pin 1 only receives power for the time the switch gets pressed. This has no influence on the dimming function of the switch illumination.
I tested the IMS Guardian without connecting the orange wires and it works flawlessly.
In my opinion, if you want the proper dimming function (on a barely visible LED because the seat heat symbol is blacked out on the IMS Guardian Switch) then you have to patch the orange lead into the 58d circuit which is conveniently available at the potentiometer of the intermittent windshield wiper function. (just look for the GY/BU/RD wire on pin 3 of the cable at the potentiometer)
Else it is not necessary to patch the orange cable into any other positive circuit.
If you have a different opinion
I would be happy to learn about it. Cheers Dom
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