Sorry to ask the question [I lost (the hardware crashed permanently and HP took 3 weeks to believe me even with all their tests --it was 1 day past store warranty but, thankfully within the 90-day HP product warranty-- and then it took HP until 4 FEB --9 weeks! to get me a new machine --wow, talk about S-L-O-W customer service! even if they did upgrade my monitor size (laptop) and my graphics card as part "compensation" for my delays along with a longer (1-year warranty) -- what a hassle)] but in the interim I had no computer available and was unable to play or eMail or anything so I have forgotten how to light (turn on) the PIP light.

So, could someone please remind me again how to turn on the PIP light? (I have spent a while looking through the Forum trying to find the original hint and can't find it even with a search.) Would appreciate it since I have been playing in the dark since last Friday night when I finally got Fallout 4 loaded and running again (had to start anew since I lost my first run --at level 12-- and now am doing the run without going through the Minutemen and Concord as I thought I'd try on a second run anyway.

Again, thanks to whoever gives me the info. Running on Windows 10 on an Intel PC. Regards and Good Hunting! RGCB

I'm on PS4 so obviously I don't know the proper key/button to press on PC but on the PS4, we simply hold the button that brings up Pip-Boy. In our case, it's the circle button. So if I hold (rather than simply press) circle, the light comes on. Hold again to turn it off.

I imagine the concept is the same on PC. Hold whatever key you normally use to pull up the Pip-Boy.

You can press and hold the button that you use to open up the pip boy.

Both previous replies are correct: hold the button to bring up the Pip-boy instead of pressing it to activate the Pip-boy Light. For those playing on the PC, the default button is Tab.