It did it to me sometime ago and at the time I unplugged the horn for it.
that was 3 years ago Now I temporarily lent the car to a friend out of town and it is doing it to them they don't have the resources available to be able to take it into a shop is there a way that the mechanically declined might be able to unhook the alarm system

I forgot to mention using the key in the door lock does nothing but the lights are flashing constantly

Passenger side front, lift out the carpet and padding, remove the black plastic covering the firewall at the front of that space. There is a single fastener I think it's a knob like thing that needs to be unscrewed to release that plastic.

Behind the plastic there is the alarm controller, made by Becker has two large multi-conductor plugs remove both plugs.

They could try the passenger side or the trunk lock, might override the driver's lock switch.

Could also try the fuse box, find what circuit the alarm is on and pull that fuse, at least that would cut the lights flashing. But other systems on the same circuit would be disabled in the process.

I checked the fuse block to no avail I will try looking under the carpet thank you very much

Don't pull the module with the RED plug, that's the airbag controller.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Well, me too. Had a broken #6 injector line while 145 miles from home. Put the car on the flatbed for the long ride home on a Sunday afternoon. When it went on the flatbed, I remotely locked the car. 3 hours later on arrival at home we rolled the car off the flatbed and when I went to start the car, dead. WTF? After a jump I got it up to the garage for service later. I put the charger on it and everything seemed fine. About 10:30 that night, just as I was about to climb into bed, I hear a car alarm going off. Sure enough, it's the wagon. Nothing would shut it off. Finally pulled the battery cable to shut it off.

Now that the injector line has been replaced, I've been attempting to resolve the alarm problem. This thread solved the problem for me by shutting the alarm and letting everything else continue to operate normally. So now what? Do I replace the alarm unit? Is there something else that needs to be reset? Wouldn't mind having the unit functional, not a worry if it remains disabled.

Then there's the issue with the injector line breaking in less than two years - that'll be a different thread.

1987 300TD, 259K miles or so.

The common failure is the security system switch built into the door latch mechanism.

Sixto
83 300SD

Do the 124 wagons have the "white plastic can" tilt sensor in their alarm system like some of the sedans did?

see thread "Viper Alarm???" it worked for me!

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Red Green "This is only temporary,Unless it works!"

97 E300D 157000 miles
87 300TD ?141k? miles