Help - my horn/alarm goes off when I put on my headlights- '90 300 SEL

[matchek1]

Please help - I am moving and need to drive the car tonight, but the alarm or horn, hard to tell which, goes off when I put on the headlights on my 1990 300 SEL.

I disconnected the alarm (underneathe the passenger side 4 years ago so I doubt it's that). But do not know.

I had a mechanic replace a rotor about a week ago and the ABS stayed on after that and also the outside temperature light does not go on as well anymore. Been busy so I haven't taken it back yet.

I took out the fuses for the "warning system" and "horn", but when I turn the headlights on, a super loud sound comes out under the hood.

Heard of this? How can I disconnect? Please help, I need to drive the car tonight.

Matt
1990 300 SEL