Switch blank adaptor to fit a 16mm latching pushbutton with a red backlight to suit the interior lighting for a VW Golf Mk6. Intended for activating LED light bar or driving lights for country driving at night.

Sparkfun latching metal pushbutton that I used: https://www.sparkfun.com/products/11971 or https://core-electronics.com.au/rugged-metal-silver-finish-pushbutton-16mm-6v-rgb-latching.html (comes in silver finish with red, blue, green, white and yellow backlight options)

Adafruit RGB latching metal pushbutton that should also fit: https://www.adafruit.com/product/4659 (comes in silver or black finish)

In Australia, LED light bars and driving lights must only come on with the high beams, but the high beams must be able to operate without the light bar, hence this switch/button.

I have wired the backlight to be dimly lit when the interior lights are on, and be brightly lit when the light bar is on. For my switch, the wiring was as follows:

• High beam (12V) -> normally open (NO) button terminal
• Common button terminal -> light bar relay
• Common button terminal -> diode -> backlight positive (+)
• Interior lights (12V) -> diode -> 30k Ohm resistor -> backlight positive (+)
• Backlight negative (-) -> ground

The reason for the diodes is so that the interior lights do not activate the light bar, and the light bar does not activate the interior lights (if I flash my high beams and light bar while the low beams are off).

I've included the STL file for 3D printing, and f3d and obj files for editing to suit your needs on Fusion 360 or another CAD packages.