Strange turn signal behavior
 

Recently, the turn signals on my '87 Carrera began to malfunction. The left turn signal works normally, but I get a "rapid blink" on the right side. If I turn the headlights or parking lights on, the right turn indicator glows softly, and there are no right-side turn signals. I have replaced both front and rear bulbs, but the problem persists.

The headlights/parking lights interact with the front turnsignals only in the bulb as they share the ground (base) of the bulb. If you turn on headlights/parking lights and the turnsignal changes, then it sounds like you've lost the ground at the front turnsignal. Did you thoroughly clean the socket for the front turnsignal?

I didn't mention the rear turnsignal because that one is a single filament 1056-type bulb and likely would not cause any interaction with the parking/headlights.

Thanks for the advice. Is there any other ground that should be checked?

Did you get anywhere with this?

It sounds like the relay is going bad. If the grounds are ok I'd replace the relay.