W203 Alarm fault? not siren??

[ET4]

Car alarm kept going off lights flashing, funny chirping etc. Disconnected the siren behind the n/s wheel to try and isolate the fault to the siren.
All back together .. seemed ok.
This lasted a whopping 3 minutes before the hazzard lights were off again thankfully with no noise ... Utterly random with no link to 'it goes off when i do this'



Has anybody any ideas before I torch it?...

 

[GP801]

Its probably still the siren. Just been through this with the CLK. Random flashing lights. Random alarm siren even when car not locked or driving along. New siren and all back to normal

 

[ET4]

I had disconnected the siren. This is what's puzzling??

 

[GP801]

Ah sorry. Misunderstood that bit. Not sure in that case unless there is some sort of secondary connection or perhaps if there is no siren detected the system assumes its been tampered with and behaves accordingly.

 

[richard]

Look for a spider (or evidence of) around the movement sensors. (no, i'm not joking !!)

Richard

 

[ET4]

Look for a spider (or evidence of) around the movement sensors. (no, i'm not joking !!)

Richard

I know what you mean but I think it's something else.
It started when my wife was unloading the shopping out of the boot. Alarm started going off with 2 doors and the boot open?
I ended up disconnecting the battery as I couldn't stop it. All connected back up and it continued from there????
Recently had the Lateral Accelaeration Sensor replaced as I had an ESP fault. Not sure if it's just a coincidence though.

 

[andy27168]

Hi,
I think your problem is as go801 has said the fact that the car can,t see a siren it activates hence the flashing lights.
You could try to turn the cars internal sensors off and arm the system at least you would eliminate creepycrawlies.
If the car was mine I would reconnect the siren and then get it put on star as this should give you an idea on what is setting the alalrm off.
Just a thought, your interior lights and boot light work as they should?

 

[sspeed]

Hate to disagree but your 203 WILL run fine without the siren connected.
The siren on my first 203 was faulty so I removed it and sealed the plug that goes into it to stop water causing any problems..
That car was without the siren for the 18 months I owned it and I never had another issue or problem..
Its a rather stupid place to have installed the siren there in my opinion.. (Under the rear of the passenger side wheel arch lining).

 

[saddlejib]

w203 as above doesnt need alarm forget the myths its only a car. Batteries can be changed saw in half using junior/small hacksaw reseal with araldite type stuff but cut posts close to battery and solder/modify new battery posts to original after cleaning the crap off the pcb. This is a good tip.
After that its good luck (hope nothings been fried).