Most photos we see of the “original” Brown Derby on Wilshire Blvd is actually its second location at 3377 Wilshire Blvd. But from 1926 to 1937, it sat at 3427 Wilshire between Mariposa & Alexandria. With that fine circa 1928 La Salle parked out front (and note: it’s the ONLY car parked on Wilshire!) I think we can date this to the late 1920s. I wish I could see all of that billboard. It’s advertising some sort of sideways-shining headlights: “Lights the turns before you make them.”
*** UPDATE ***
It looks like the billboard was advertising the Pilot-Ray safety lamp. You can learn more about it here.
Classic LA architecture.
I believe that may be an ad for the Pilot Ray Automatic Safety Lamp.
https://i.imgur.com/Zu6VaLz.jpg
The full ad in the paper from 1929 can be seen here: https://stanforddailyarchive.com/cgi-bin/stanford?a=d&d=stanford19291021-01.1.4&e=——-en-20–1–txt-txIN——-#
Well done, Sherlock Yuma!