THe wiring diagrams are VERY incomplete and inaccurate when it comes to a lot of things, and THAT circuit in particular.

I gave up some time ago, they leave too much detail out - but as far as I can tell, the flasher for the fourways is the flasher for the turn signals. My guess would be the flasher is bad or the four way flasher SWITCH is bad.

I do not know where the damn flasher is, either. I THINK it's in behind or plugged into the four way flasher switch but I can't say for sure.