Thanks Gilly !
I haven't pulled the wiring schematics out yet but was going to pop the cover off that box and do some simple voltage checks at the fuses.
1992 500E Smoke Silver
2002 CLK55 AMG Cab Silver/Black
2001 Harley Fatboy - Pearl White
2004 F150 FX4 Silver/Grey
1969 GTO Liberty Blue
1956 F100 Black