Flashing side lights

[Tbob]

I’ll resurrect this thread, since it already has useful info posted.

I made this mod (2003 986), but there is a small problem. One side marker works fine in all modes (no lights, parking lights, turning) but the other side does not flash unless the parking lights are turned on. If the parking lights are on it illuminates, and it flashes when it’s supposed to. I swapped lights, bulbs, no different.

My big question is really this: I don’t understand how the modified circuit can light the bulb at all if the parking lights are off. There’s no connection to the + side of the bulb. When parking lights are on there is +12v, so everything works. Any electrical pros out there who can explain it to me?