1986 560sl Headlight won't turn off when the car is shut down
I have a 1986 560sl with about 140K miles. Recently it was found that the headlights won't go off but stay on after the car is shut down. The headlight switch seems working find, as when the car is running or the key at the ON position I can use the headlight switch to turn on or turn off the headlights with no problem. Only when I take the key out of the ignition switch, the headlights will come ON no matter which position the headlight switch is at.
It seems to me kind of relay related, but I couldn't figure out which relay contributes to this and where it is located.
Any advice of how to diagnosis this problem would be highly appreciated.