I have a strange problem... when I turn on my parking lights or headlights, I can't use my turn signals. When I turn on the right side, they blink once and then stay off. When I turn on the left side, nothing happens. If the lights are set in the "off" position, both sides work fine.

BTW, the same is true for emergency flashers as well.

Any ideas? I've already checked fuses and relays, and the bulbs are good too.