1993 W124 Alarm Question
 

This morning at 5 am my alarm went off for apparently no reason.

No glass was broken, no doors looked like they had been prised apart or anything else out of the ordinary.

By the time I got outside(maybe a minute after it went off) there was nobody around obviously.

I didn't hear anything before the alarm went off and my dogs didn't make any racket before it went off.

My question is whether or not there is a known fault I should be concerned about that would cause this to happen assuming nobody or nothing actually set it off?

Thanks for the help

They go crazy after 17 years, and it is most economical to disable it as opposed to fixing it as it could get pricey, fast!!

This might help if you decide to disable it

http://www.peachparts.com/shopforum/showthread.php?t=269799&highlight=disable+alarm

Using the valet key instead of the master key to lock the doors will not arm the alarm.

Both of my 87 diesels I use this approach.

I am having a similar problem with my 1991 300E's alarm going off for no reason.

I have located the alarm under the passenger foot rest. Do I need to disconnect my car battery prior to unplugging the connections to the alarm?

Also, I believe there is a separate horn for the alarm. Does anyone know where that horn is located in the car?

Not sure, but ,yes, I would disconnect the battery (remember you code for radio).

I am also not sure about the horn, but i did not have an issue with that as seen in the thread.....

IIRC the horn is behind the left headlamp.

Do you have an aftermarket stereo? if so the alarm ground may be hitting something if they did not tape the end off or just cut it.

What if I don't know the code for my stereo? Is there a way to find it?

Smokey, is your stereo the stock for your 1991? With the nice bass speakers in the doors? Should be the Becker 1432!

When I first bought my car, I didn't have the code either. I spent hours scouring the internet. Finally found a program that takes a BE1432 serial no and turns out your four digit code! What is your radio serial? I have no idea if I still even have the file, but I'm pretty sure I saved it. I know I was unable to find it when I looked again recently...just searching the net.

Are the W124 door handles like the W126 ones? My owners manual says only the master key with the red dot on it will arm the alarm, but any key in the lock will actually arm it, and if you turn the key slowly enough you can arm the alarm without locking the car! The arming mechanism is very simple, just a pair of microswitches in the door handle. I don't know how they could detect a valet key...

-Jason

There is a non-stock head unit (Pioneer) on the car so I am assuming the entire stereo was replaced at some point. I really don't know though.

When I pulled up the passenger footrest area, it looked like a bunch of cables were unplugged already.

If you have an aftermarket radio, the radio code no longer applies. :)

Alright. So I completely removed the becker unit from under the passenger footrest. After removal, I taped up all the remaining electrical connections with electrical tape and threw the Becker unit in my tool box. There is no reason to keep it in the car right?

To test if the alarm would no longer go off, I rolled down the windows, locked the car, then reached in and opened the driver side door handle - no alarm! So I am hopeful my alarm problems are solved.

I also tested the radio as well as drove the car a little bit. No problems. Thanks for all the help!

A good way to test is to open the hood with engine off, and press the hood alarm switch ...if it still working, it should go off....ask me how i know!!!

My alarm problem is happening more often now and I am also having battery problems.

The last few months if I don't drive the car much for three or four days the battery would be dead.

However, yesterday I drove about 200 miles and my battery was dead this morning.

My alarm also went off for a few minutes this morning as well.

My question is whether or not my battery/charging system could be causing the alarm problem or could it be the other way around?