Illuminated lighting always active on a switch?


I am wondering is the illuminated light always on or on only when the button is pressed? The switch I am wondering is following:



Thank you for your help!

Welcome to the forum.

The SW-PB7-07LB42CRRR12V, like most illuminated switches, has four terminals, two for the lamp and two for the switch.

You can wire the circuit so that the switch controls the lamp or you can wire the circuit so that something else controls the lamp (e.g. micro-controller).

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Hello oivanenmarco,

There is a broader question of “what controls the indicator lamp?”

This is not a trivial question when we design for reliable real-time operation. It’s important and can impact the safety of a design.

Please allow me to introduce Dr. Michael J. Pont.

It’s been years since I first watched this video, but I still remember his explanation starting at time index 1:11:45.

The software should be in control!

Best Wishes,


P.S. you may want to download a copy of his Patterns for Time-Triggered Embedded Systems book.