W202 alarm

[djcheung]

Hi all,

The alarm on my wife's 95's W202 has just developed a odd symptom.
Two days ago, whenever the alarm was armed/disarmed, only the left hand side indicators were flashing ( all other functions are working fine). Tested the indicators for normal use and they are working ok. Yesterday the problem switched over to the right hand side. Any ideas?
Is it something to do with the alarm unit and where it is located?

 

[djcheung]

Does anybody know where the alarm is located?

 

[reflexboy]

The alarm on a W202 is under the bonnet, near the front on the right hand side if you are looking at the car fromt the front.

 

[GazCaff]

The alarm on a W202 is under the bonnet, near the front on the right hand side if you are looking at the car fromt the front.

Isn't that the ABS pump?

 

[bobrooney]

The thing in the middle?

 

[djcheung]

I have a similar unit but difference looking then bobrooney's. But it is just the siren for the alarm. My problem seems gone permanent now. All of the right hand side indicators are not coming on when the alarm arms and disarms including the right hand indicator on the dash. Normal indicator usage are ok though. Any thoughts?

 

[grober]

DREADED SCOTCH- LOCKs

Normally the alarm ties into the indicator circuits on both sides in order to power the indicators to flash as an indication of setting/unsetting the alarm and to flash them when the alarm sounds. The alarm connections are often tied into the existing indicator circuits via the dreaded Scotchlock connectors which can work loose over time. Where exactly this tie in occurs depends on the alarm design and also the installer. This is whats probably happened in your case. The indicator/hazard warning light circuits will remain working fine.

 

[djcheung]

Thanks Grober,

One more question. Where is the alarm located and what does it look like ( I believe it is one installed by MB). If I know where the alarm is then at least I can trace the cable to the connection and hopefully fix it.

 

[grober]

black box

The alarm control unit can be located in several places. Its not usually easily accessible for security reasons. On the w124 series its usually behind the dash board on the drivers side. I believe on the w202 series its either there or below the floor covering or side kick panel of the drivers foot area or possibly beneath the rear seat. It depends on the installers preference. It will usually be a plain rectangular "black box" Close inspection will reveal the wiring coming from it will be slightly different from the standard MB wiring. The 2 indicator wire connections are possibly orange in colour and may be fused. Maybe other w202 owners can be more specific? Be prepared to remove quite a lot of interior trim to access it

 

[Dec]

I have a black box which I think is the alarm "brain" in passanger footwell, lift the carpet and you will see a foot rest secured by 3 screws/bolts, remove this panell and you mighr find it there,I know nothing about the wireing, my siren is a single red siren and is not the same as the one in bobrooney's photo.
Dec

 

[djcheung]

Hi Dec,

My siren is red as well, maybe the control unit is underneath the passanger carpet same as yours. I will look at it over the weekend and see if it is just loose connection.

Thanks.

 

[bobrooney]

I've been having problems with my alarm as you can see from this thread http://mbclub.co.uk/forums/showthread.php?t=26621
My indicators were not flashing at all when the button was pressed on the key fob. After reading this thread I had a look for the alarm under the front passenger footwell.

Removed the side panel, then the carpet. There was a metal panel which I had a feeling might have been where the alarm was. I checked this by pressing the key fob button and heard clicking noises coming from it. So unbolted the panel and there it was.

There were two fuses. One of them, a 10A fuse, was gone. So I changed it and now the indicators are flashing when the key fob button is pressed, but still no alarm siren.

I've taken a picture of the alarm but I'll post this later as I'm in a rush at the moment.

 

[reflexboy]

My alarm siren looks identical to Bobrooney's but is located right next to the abs pump.

 

[djcheung]

I lifted the carpet on the passenger side over the weekend. Undo the nuts holding the metal plate and found a device that doesn't look like an alarm control unit. As far as I can see was only two trunky wires connected to it.
Any other suggestion?

 

[Dec]

As Grober says it could be anywhere, any coment on the pictures in this post herehttp://mbclub.co.uk/forums/showthread.php?t=26621&page=2