I had a problem with my right signals coming on by themselves and just staying on solidly. It was the wires in the right front signal/Parking light assembly. A case of disintegrating insulation. When the headlights were on the wires shorted power from the right parking lamp wire to the turn signal wire.

I originaly thought it must be a tail light assembly problem, but there was power at the rear signal lamp and at the turn signal switch terminal. Pulling the wires off the switch had no effect so the power was coming from somewhere else. Next I unpluged the cable to the the rear harness and the rear signal went out but the front and indicator stayed on. Checking the front light assembly revealed the problem.