In California if the traffic light breaks down then you're supposed to stop as if there was a stop sign; all the same rules apply.
But a broken traffic light is a situation that is unfamiliar to drivers, and at peak hours the crossing is guaranteed to be either difficult to navigate or to have suboptimal traffic patterns (otherwise there would be no traffic light in the first place). And of course pedestrians have to improvise (and Germany has a lot of pedestrians compared to the US)