laser alarm problem

[softtop]

When i bought my 1990 300ce-24 many years ago i would marvel at the cool total closure alarm system. Then one day it just stopped working.

Central locking works but only from the key in the door. The red LED on the left of the steering stays on and I have to keep the system disabled by switching it off from the key at the back of the glove.

If i turn it on at the glovebox key the led will flash about 6 or 7 times and the alarm will go off.

The keyfob has a new battery and a small green led on it flashes when i press the rubber button. The fob has a 'tuning screw inside'.

Please can anyone give me any clues as to where to start diagnosing possible problems. Is it something as simple as a sensor on the door or boot not registering that it is closed or is it much more complex.

I've read about toad replacements on the site. Is this the way to go and will i keep my total closure system?

thanks, Soft Top.
Black met 1990 300ce-24
rosewood 1994 e320 AMG cabriolet

 

[softtop]

alarm help

Any alarm experts out there. just a clue of where to start would be useful.

 

[softtop]

Resolved!!!

I thought I'd post this in case someone else had alarm problems.

My laserline model 911 alarm had stopped working some time ago. Thinking about how it must sense that all doors and boot are closed I decided to investigate why my boot light had not been working.

With multimeter in hand and after stripping out various bits of lining trim from the boot i located a broken wire in the plastic cable pipe that runs from the boot hinge into to the underside of the parcel shelf (there was no need to remove trim after all!). Having resoldered this wire the boot light was working and the alarm was armed when switched on.

To reset the alarm I closed all the doors and locked the car manually from outside. Even though i put a new battery in the key fob, it did not work until i slightly twiddled/tuned the rheostat in the key fob.

Presto - a working alarm system with total closure - i'm well chuffed.