2015 E220 alarm problems

[ColinHaydock]

I own a 2015 E220 and I am having problems with the locking. When I get out off the car and press the button on the key to lock the car, the alarm makes a sound like the horn, the doors lock but the alarm does not set. Instead the indicator lights flash quickly and keep on flashing. If I press the locking button again on the key, the indicators flash 3 times (as they should) and the car is then locked.

 

[John Laidlaw]

Welcome Colin
Think I’m right in saying the alarm has its own battery, so it’s possible it’s on the way out ?

 

[AMGeed]

^ As above. I would suspect the internal battery. I'm unsure if Star can detect this fault or not though. A new siren is £100 from the main dealer and easy to DIY. It's inside the front o/s wheel arch liner.
The horn blow on locking is annoying and can be turned off in the system menu on the dash.

 

[ColinHaydock]

Welcome Colin
Think I’m right in saying the alarm has its own battery, so it’s possible it’s on the way out ?

Thanks for the reply. Is that the auxiliary battery which is located in the boot or is there another battery actually located inside the alarm?

 

[ColinHaydock]

^ As above. I would suspect the internal battery. I'm unsure if Star can detect this fault or not though. A new siren is £100 from the main dealer and easy to DIY. It's inside the front o/s wheel arch liner.
The horn blow on locking is annoying and can be turned off in the system menu on the dash.

Thanks for the reply. When you say internal battery, is that contained within the siren? i.e. not the auxiliary batter which is located in the boot?

 

[spenttherent]

In the siren behind the wheel arch liner

 

[AMGeed]

Thanks for the reply. When you say internal battery, is that contained within the siren? i.e. not the auxiliary batter which is located in the boot?

As above, its the internal battery in the siren itself. It's not replacable and a new siren is the answer.

 

[Vikki003]

^ As above. I would suspect the internal battery. I'm unsure if Star can detect this fault or not though. A new siren is £100 from the main dealer and easy to DIY. It's inside the front o/s wheel arch liner.
The horn blow on locking is annoying and can be turned off in the system menu on the dash.

Can this actually by DIY or does it need to go to Merc for the coding please? We are struggling with ours, it woke our neighbours at 1:30 this morning and we couldn’t get it to stop!

 

[Droverunner]

I had exactly the same on my 2012 Viano when it arrived here after being out of regular use for many months. While wondering about a problem with the alarm unit internal battery and associated circuit damage I coincidentally fitted a new main battery and started using the vehicle daily. The problem went away and has been fine in the months since without changing the alarm unit.

 

[mioba]

Can this actually by DIY or does it need to go to Merc for the coding please? We are struggling with ours, it woke our neighbours at 1:30 this morning and we couldn’t get it to stop!

Its a DIY if you can get the car up. Wheel off, liner out, remove wires to old unit, bolt off unit, reverse order to fit new.

The siren is a control module for the alarm and has a battery inside and circuit, either is known to fail.

Best bet to get if off the drive and at indy to do the work so you are not disturbing the street.

 

[Vikki003]

Its a DIY if you can get the car up. Wheel off, liner out, remove wires to old unit, bolt off unit, reverse order to fit new.

The siren is a control module for the alarm and has a battery inside and circuit, either is known to fail.

Best bet to get if off the drive and at indy to do the work so you are not disturbing the street.

Thank you very much

 

[AMGeed]

Can this actually by DIY or does it need to go to Merc for the coding please? We are struggling with ours, it woke our neighbours at 1:30 this morning and we couldn’t get it to stop!

No coding is required for an alarm siren replacement. Once you have found the location (o/s or n/s front wheel arch next to the bulkhead on most models) its an easy swap over. You may need a torx bit (the one with a hole through the centre) to disconnect the siren from the wheel arch. Screwfix sell a box with all sizes for under £10 IIRC.

 

[Vikki003]

No coding is required for an alarm siren replacement. Once you have found the location (o/s or n/s front wheel arch next to the bulkhead on most models) its an easy swap over. You may need a torx bit (the one with a hole through the centre) to disconnect the siren from the wheel arch. Screwfix sell a box with all sizes for under £10 IIRC.

Thank you very much for your help.