Hmmm, kind of unusual because the same bulb filament serves BOTH the blinker and the brake function. It could be a short in the wire from the brake switch leading back to that particular bulb and if the left brake light work okay it would have to be somewhere AFTER the wires leading to the rear lights branch off from one another. Are you CERTAIN that the right rear signal blinker DOES work?
You probably have a turn signal or light that is burnt out
Problem most likely is in the Turn Signal switch. I had same problem , replaced Turn Signal switch assembly and that fixed it.
The turn signal flasher is what makes the noise and lets the turn signal flash.
often the blinker is made to blink faster when there is a bulb burned out
Question: Does the turn signal blink on the right rear? I suspect not. Both the brake light and the turn signal use the same filament. If one is burnt out, the other will not work either. If so, the bulb needs replacing.
your problem could be in the switch its self. unfortunetly they are expensive to replace, i had to actually wire a switch direct to the blinker system.
Most likely turn signal flasher needs to be replaced
on my blinker turn signal
Get a new blinker unit.
The only answer I can find in the manual is when the dashboard "maintenance required" signal appears. I'm thinking it's around 5000 miles, but I don't know for sure, as I just got my 2005 Highlander recently.
Most common problem -turn signal flasher
i got the same problem with my 99 Audi a6.