Hi all,

I have browsed this site a number of times but this is my first post, as I have been unable to find a solution to my problem. As some background to the vehicle: I own a 2010 A180 CDI Avantegarde which I bought second hand when it had only 35 000km on the clock. It is now at about 230 000km. I have it serviced at its scheduled times. When it was under warranty, it went to the official merc workshop in my area but, since the warranty expired, I have been taking it to RMI approved service stations. I recently discovered a garage close to my workplace owned by a guy who was a diesel mechanic at Merc for 10 years, so for the last service I took it there. It is due for a service soon and I will take it there again. I have had zero mechanical problems with this vehicle and it really is in good condition. The only thing that has been going wrong, was that the aircon needed to be regassed (there might be some other problem related to the aircon, not sure - will keep an eye on it) and now this problem with the heated seats.

The car comes with heated seats in front (butt side of seats, not lumbar). I wanted to switch my seat on this morning and noticed that the switch would not light up, and of course no heat. I checked the passenger side and it was doing the exact same. I am not sure when last I used it successfully, as it has been summer but I had no problems with this before whatsoever. The fact that both seats are not working and that the switches do not even light up leads me to believe it could be something to do with the fuse. However, I checked the fuse box and diagram (it shows heated seats as fuse 49) but there is no fuse in this fuse slot. The seats have been working all these years, so I don't understand how it worked without a fuse in the first place and this is clearly where I am having a problem diagnosing the problem as I don't understand how a feature works without a fuse.

I've been browsing the internet for solutions and found a site where a few people had indicated that their coolant light lit up, and that at the same time the heated seats stopped working. They indicated that this happened even after all coolant related possibilities had been checked and fixed where necessary. Then, after a lot of digging and reading, I found a site where someone pointed to a fuse on the positive terminal of the battery itself. It appears that many people had successfully solved this problem by replacing this fuse. I have checked the battery and there is no such fuse on it. The battery was recently replaced (not by a merc dealer, just a normal battery centre). Please note, though, that I did not have any problems with coolant lights or anything else lighting up on the control panel.

Is it possible that the original battery could have had such a fuse? If so, is there any way that I can check for anything that should have been connected to this fuse on the new battery that is now not connected. I have looked around the side of the battery and do not see anything that appears to be disconnected. Should I connect a fuse to the 49 slot in the fuse box as per the diagram - could this possibly work?

I am quite sure that it could not be the heating elements in the seats that are faulty as it seems pretty unlikely that they would both go at exactly the same time (passenger seat almost never used), and that both switches would not light up at all. It seems more likely to be something electrical in terms of the feed going to the switches but I don't know where to start. Any ideas, please?

Regards
B

 

Hello,
i have the same problem
I replaced the fuse number 49 with another but apparently the new fuse was bigger in voltage and that caused a shortage of power, i then put in the correct one and now only the passenger seat works. The drivers one does not light at all but it stays on all the time

However i noticed that it is turning on and never turning off.
i had to remove the fuse to save myself from burning.

Where is the relay for the heated seats in the w169, anyone has any ideas?