lights turn on during the night while parked up.

[Dennis Day]

Morning all, been a while. I have a problem with my C class 220 CDI estate 2008. The sidelights randomly switch on during the night. My neighbour first pointed this out so I tried to switch them off but they would not respond. I had to disconnect the battery to get them off, meanwhile, the battery went flat. I recharged the battery for 24 hours and all seemed fine then last night, the same thing. Any ideas would be greatly appreciated, thanks.

 

[mioba]

could be many things, faulty switch, faulty light sensor, faulty relay, faulty sam.
Get to a garage with star/xentry and have the codes diagnosed, otherwise you will be throwing money at bits for something small (hopefully)

 

[Dennis Day]

Thanks for the reply. I have had previous problems whereby when the switch was on 'auto' whilst driving, the lights would switch on and off frequently. When switched to off, no problem. I will do as you suggest and hopefully find the fault. Bit of a nuisance as the battery is flat each morning!

 

[Blobcat]

Water in the electrics is what I'd be looking for with your symptoms

 

[Dennis Day]

Funny you should say that, I just noticed that I had left the cover off the fuse box under bonnet when changing a fuse for the cigarette lighter in glove box, but I haven't driven it since then. If this is the prob will it help to run a hot air gun over it?

 

[Blobcat]

Funny you should say that, I just noticed that I had left the cover off the fuse box under bonnet when changing a fuse for the cigarette lighter in glove box, but I haven't driven it since then. If this is the prob will it help to run a hot air gun over it?

Depends where the water has got to... if it's in the SAM then the board will no doubt be green and corroded which hot air won't fix unfortunately.

 

[Dennis Day]

You've cracked it my friend, water has got into to area closest to the bulkhead, 40amp fuse waterlogged but not blown, no fuses are blown. One suspect relay, small black one marked 8107. Thanks very much indeed for your help.

 

[mioba]

ps dont use a hot air gun, that will melt things and they run far too hot, A hair dryer is best.

Disconnent battery

Take everything out, take pics first so you know where it all goes back.

Lay all the bits out on a towel outside, pref with some breeze to help the drying.

Dry and clean the box/connection, spray with somecontact cleaner and resemle all when dry.

Hope nothing has corroded. If so replace.

 

[Dennis Day]

Found 1 damaged/corroded relay, picked one up from Mercedes £9.60, I just hope that solves it, got to wait for the battery to recharge. Thanks for the help.