R170 SLK230 Indicators stop flashing infrequently

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New Member
Nov 12, 2011
SLK230, SLK 32AMG, C200CDI
I have been putting up with the flashers/indicators occassionally stopping working. The hazards still worked. I have known for some time the problem was assocaited with the Illumination module in other words the headlight switch control unit as if I tapped it they would often start working again.
The problem got worse and I took the module out. The problem was around Fuse 12 and if this was wiggaled the inidicators worked or stopped working. The module plastic covers un-clip easily and the cover to the fuse sockets can be taken off readily. The fuse sockets themselves together with their plastic base didn't want to come off.
It turned out both sides of F12 had intermintent connection to the green flixible pcb and so instead of buying a new unit I soldered a flying fuse socket (from maplin) directly to the PCB and bypassed the doggy socket. If you hold the unit with the fuse sockets towards you with F12 to the bottom right, the the green varnished copper track to the right of F12 is the top contact and the first solder contact below and right is the lower fuse contact. (if you look at the botton of F12 where it joins the flexible green pcb, you can see where it goes (and also can chcek with a conductivity multimeter). Scrape of the green varnish and solder a wire from the replacement fuse holder for the top contact then solder the other fuse holder wire to the bottom contact. I found the solder used by Merc took around 350Deg C to solder properly if u have trouble.

I hope others find this useful.

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