The 928 has a capability to have daylight driving lights on. Basically when you turn on the car, and the engine runs, the lights come on.
Starting MY 1990 (!!) you can just plug in a special relay in Relay Socket
III. The power is taken from after the fuel pump relay, just where it
feeds the pump, so when the engine runs, the relay comes on. The relay is
special in such a way that it contains a diode, thus preventing the light switch
to feed the pump when the fuel pump relay is off. (obviously you want to leave
fuel pump control to the LH ecu and nut bypass that.)
Have a look at the schematic at G89/G90. Label F8 goes to the light circuit.
Thanks Gordon (PFF) for bringing this to our attention and making a picture of it.