Anybody here have any ideas about this....

Whenever I plug in the alarm it drains my battery and makes a screeching noise from under the passenger carpet where the plugs are.

Any ideas on how to fix this or tests to find out what's wrong? I don't know anything about the alarm system in the w124.

I'd like to have the alarm functional again if possible as I have to park the car on the side of the street now as the apartment complex issued me a warning because of my oil pan leaks. (gonna fix that over new years)

Thanks!

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

If you care to be educated of the MB antiftheft system I can send you some documents about it.

Your module could be shot and have shorted or something went inside.

there is a test program for the antitheft that only requires a DVOM. I can send you that as well.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

One way to check the battery is to recharge it, then let it sit for a day with both battery cables disconnected. If the battery holds the charge and doesn’t run down, it’s probably okay, and the problem is in your charging system or wiring.

I did replace my alternator that died about 6 months ago. Maybe it was weak and the alarm made it lose charge when it was plugged in?

Also if you could send me that info on the alarm I would love to learn it!

Much appreciated.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Plugged it back in today and I was wrong it was not a screeching noise its a ticking noise. It sounds exactly like an indicator and it ticks constantly.

You think its the unit?

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

If it's the same as in my car (Becker box, last digits in part number = 26), then there are a few things that could be wrong.

There are 4 relays in there. 3 for flashing the lights, horn, etc... and 1 that determines if the system is armed or not.

If you have electronics skills, start by checking the little 100uf@10v electrolytic capacitor. If this is shorted, it will cause a current drain.

The ticking sound is probably one of the relays cycling on and off. It wouldn't be the arm/disarm relay as that one is nearly silent.

Does the ticking occur at roughly the same rate as the alarm would beep or the lights would flash? If so, then the alarm is constantly going off, and for some reason not actually honking or flashing.

After doing some basic troubleshooting of all the sensor wiring, etc. I would just try to find another alarm box on Ebay. They're usually $40 or less for a used one. Just be aware, these things do tend to develop issues over time.

I could print out the alarm troubleshooting flowchart for you if you want.

-tp

I sent you the test program for the antitheft. Run through that program and see if anythings sticks out. theres also a tests the function of the antitheft which is in the document explaining how it works. run that.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)