Tom,

No, I don't think you'll find a wire in the US harness for that 3rd bulb. You could however, run a 6-inch wire from pin 3 of the main light connector to pin 4 of the corner parking lamp connector. (Assuming same arrangement as on a W124.) This would give you 'city lights' when your parking lights are on.

I use the fog lamps as my DRLs.

Barrie