S4 TII.......

What do you think of these symptoms?

Engine on...........Headlights on..............Engine WON'T shut off
Engine on...........Headlights off..............Engine WILL shut off

Engine off...........key to "On"............dash lights on........ DIM
Engine off...........key to "OFF"...........dash lights on........brighter (normal)

Thoughts please? Bad ignition switch? 12v bleeding over somewhere?

 

sounds like ignition switch is bad

 

Take a look around the underside of the steering column for bad/melted wires. There's not too many things this could be. Pretty much just the switch and wiring.