Check the wires to the windshield header light and see if you can find one that's always on; the one that actually powers the light is, after all, controlled by the door courtesy light switch. On my 560SL, the wiring follows the same path, but as I think of it I think I recall a wire(s) that bypasses the lamp to go to the mirror. Just had the header trim off this evening to tighten up the visor, but didn't pay much attention to the wiring.

__________________
Craig Bethune

'97 SL500, 40th anniversary edition

'04 Olds Bravada (SWMBO's)
'06 Lexus ES330
'89 560SL (sold)


SL--Anything else is just a Mercedes.
(Kudos to whoever said it first)