Lately while sitting at a light with turn signal on in my '86 535i they stop "clicking" and flashing the green arrow. Seem to work initially and go dead after 12-15 flashes. Then they won't click or flash. Try them some time later (10 minutes) and they may work again. Happens when the turn stalk is partially or completely activated. Where is the best place to start to hunt down the culprit?