Alarm Siren Replaced, Still Going Off

[Hawkwind]

As per the title really, though it's a bit of an on-going saga ( those with little patience may want to skip the background info ).

So bought the car about 6 months ago (W208) and occasionally the hazards would flash, this would eventually kill the battery.

After enquiring on here, I found the siren was disconnected, so reconnected it, tested the alarm and everything seemed to work and also to my relief the alarm didn't go off at 03:30 in the morning.

All has been quiet and calm until my neighbour informed my wife that the car alarm woke him at (yes you guessed it), 03:30.

So to oblige him I disconnected the siren and the following day the cars battery was flat.

On my days off, popped to Mercedes and bought a new siren and fitted it, tested and all was well until 23:30 last night, off it goes again for no reason

I was baffled, but then a thought occurred to me, the radio reception has been crappy since about the time I first played around with the siren and also I noticed the vanity mirror illumination no longer works.

I'm thinking there must be a blown fuse somewhere, but could a blown fuse be causing the problem with the alarm?

Any help would be greatly appreciated, right now I have a choice of no sleep, or leaving the car unlocked,neither of which is ideal.

 

[markmifsud]

Why not get diagnostics carried out on STAR? it will tell you what caused the last activation.

 

[Dec]

You could return the new siren and claim it’s faulty, it is a possibility, and this might cause the dealer to either exchange the unit or test it on STAR if it’s still connected to the car.

Do the hazard lights always flash 3 times when you lock with the remoter?

Which siren did you get?

Dec

 

[gbjeppm]

On the 203, the alarm and antenna booster were on the same fuse, so when I pulled the fuse to stop the alarm drain, radio reception disappeared.

So your fuse theory could be good. On the 208 I have a feeling these are in the boot, and the fuse diagram is inside the boot fusebox cover.

 

[Hawkwind]

I'm away at work right now, but I'll check all the suggestions.

I did already check the fuses in the boot though and they're all good. Once I get home, I'll take a look at the owners manual to see where the other fuses are located, especially the one for the vanity mirror lights.

If I get no joy I'll get it hooked up to STAR. How much will MB charge, or would it be best to go the indy route?