I had the same problem with my 92 190E 2.3. Since your alarm is mot working properly anyway you should relace or simply remove the alarm control unit.

The alarm control unit is located on the passeger side UNDER the carpet on the incline where your feet rest. Pull out the carpet - it has a "snap" just in front of the seat. Then there is a plastic cover that has a plastic nut.
Remove the cover and unplug the alarm control unit.

Its a 5 minute job.


I hope this helps
John Mlynick