Comment by toast0

It's well spelled out in vehicle code 21453 (a)

> A driver facing a steady circular red signal alone shall stop at a marked limit line, but if none, before entering the crosswalk on the near side of the intersection or, if none, then before entering the intersection, and shall remain stopped until an indication to proceed is shown, except as provided in subdivision (b). [subdivision b allows for turns on red]

https://leginfo.legislature.ca.gov/faces/codes_displaySectio....