Bonnet OPEN on dash read-out

[JenAl]

Hi. Wife's 2008 SLK200 (R171) has locational "bonnet open" read-out on the dash. Need to slam the bonnet closed to remove the message.

Is there an adjustment (micro switch/sensor etc) that needs attention?

Thank you
Alan

 

[sailorjim]

Now driving my second merc. They both needed a hard slam to close the bonnet. I think it's a characteristic of the make.

 

[AndySlade]

Have you tried lubricating the bonnet release catches and microswitch?

 

[anyweb]

as above, some squirts of wd40 should help, i used to slam my w212 bonnet really hard thinking it was faulty, it just needed some lubrication

 

[JenAl]

Thank you all for your replies. Yes, both bonnet release catches are very well lubricated (with grease). AndySlade - where is the microswitch located?

Regards
Alan

 

[JenAl]

2008 SLK200 (R171).
When I park the car up for a period of time (more than 4 weeks), I always disconnect the battery at the -ve terminal. Reconnected this terminal this PM, and started the car. No problems. Now I disconnected the -ve terminal again at the battery and horns start bleeping and the hazard lights are going. So with the battery disconnected, what is powering the horn and flashers?
Regards
Alan

 

[Blobcat]

2008 SLK200 (R171).
When I park the car up for a period of time (more than 4 weeks), I always disconnect the battery at the -ve terminal. Reconnected this terminal this PM, and started the car. No problems. Now I disconnected the -ve terminal again at the battery and horns start bleeping and the hazard lights are going. So with the battery disconnected, what is powering the horn and flashers?
Regards
Alan

Car alarm battery

 

[JenAl]

Thank you Blobcat for the reply. Where do I find the location of this battery?
Cheers ...> Alan

 

[Blobcat]

Thank you Blobcat for the reply. Where do I find the location of this battery?
Cheers ...> Alan

It’s integral to the alarm unit, probably hidden up behind one of the wheel arch liners

 

[JenAl]

Thanks again Blobcat.

Regards ...> Alan

 

[AMGeed]

2008 SLK200 (R171).
When I park the car up for a period of time (more than 4 weeks), I always disconnect the battery at the -ve terminal. Reconnected this terminal this PM, and started the car. No problems. Now I disconnected the -ve terminal again at the battery and horns start bleeping and the hazard lights are going. So with the battery disconnected, what is powering the horn and flashers?
Regards
Alan

The internal batteries have probably corroded inside the car alarm which should be located behind the n/s/f wheel rear arch lining against the bulk head..
Item #10 in the diagram below (link is for a LHD car so its on the passenger side)
Its a simple matter of unbolting the old unit , unplugging the connector and replacing with a new unit from Mercedes. Last I looked they were around £120.
You may need security torx bits to undo the bolt.

FG 171.442 - ANTI-THEFT WARNING SYSTEM,TOW-AWAY PROTECTION,PASSENGER COMP.PROTECTION > Mercedes EPC Online > nemigaparts.com

Parts catalogs. Spare parts catalog Mercedes EPC Online. Mercedes. Car. ANTI-THEFT WARNING SYSTEM,TOW-AWAY PROTECTION,PASSENGER COMP.PROTECTION.

nemigaparts.com