Turn signal on left rear side doesn't work...

Hello,

I have a 1990 Accord. My left rear flasher/directional is not working.
I
can hear the flasher relay clicking at twice the normal speed. It's not
the bulb. As all the other flasher lights are working, am I correct to
assume that the flasher relay is not the problem? I'm trying to figure
out the wiring from a "Haynes" book, but that's never easy. It looks
like
the ICU might have something to do with the directionals.

Amy help is appreciated.

Thanks. dave