Wiring the driving lamps to go off when low beams are on is easy. Wire one side of a relay coil to the low beam wire and the other side to the switched terminal on the driving lamp switch. Wire the relay common to +12V and wire the relay NO terminal to the driving lamps. The relay coil gets its ground through the low beam filaments except when they are on. The driving lamp switch should get its power from the ignition accessory terminal to prevent any current flow if you forget to turn the driving lights off.
Baldy
