2006 W203 C280 4Matic. Directional flasher on side view mirror not working for several years. Recently, washer pump died. Tested pump, it's good. Only getting 2.5V at washer pump socket. Car running, not running, key turned, washer button (stalk) pressed-in, ect but always a 2.5V reading. Tested battery and grounds under the hood 12.6V on all three. Removed side mirror case, inspected and sprayed with contact cleaner all wires and contacts. Removed directional/washer stalk end cap, inspected and sprayed with contact cleaner the mini circuit board and sliders for washer and wipers. Removed, visually, inspected and sprayed all fuses and relays and the slots the fuses/relays plug into. I'm a novice with limited knowledge. My question is, what is the probability that replacing the combination switch behind the steering wheel will solve both of these issues? I'm sure there are additional. more comprehensive testing that can be done with a multimeter to isolate/identify the problem but I'm already close to pushing the my limits dealing with electrical puzzles.

 

This is a nasty one.

If the stalk was dead, then all the blinkers would die (not just the mirror).

The combination switches are known to die here and there. Can't go wrong with replacing it, which will probably fix your washer problem. Honestly I'd start there first.

If the stalk replacement doesn't fix the mirror blinker, it's either a wiring issue (as in something chewed through a wire), or there is a problem with the front SAM. Good luck.

 

Not 100% sure about washer stalk, but my iCarsoft reads most if not all the states of switches in the car
in real time. Push a button, it changes state on the screen. Every switch in the car is tied into the CANBUS.
Pretty damn impressive? Or just too f'ing complicated I'm not sure.
But I'm thinking perhaps your next step would be to see if CANBUS is registering switch changes
on the stalk using whatever scanner floats your boat. I have the iCarsoft MBII.
I has disappointed me in other areas, won't clear my SRS error after replacing the steering wheel,
and says my MB error codes are unknown. Unknown? Isn't that what I paid THEM for?
OBD works fine, and live data is pretty f'ing cool. Good luck!
Some complete *** sideswiped my car in it's parking place (a jinxed spot it turned out, 2 other cars
were smashed in the same spot). They knocked off the bumper, and destryed the side marker which I was able to
fix, but the washer tank leaks and gives me the washer low error every week or so.
I have a picknpull replacement tank ready to go in one of these days, need to pull the bumper to do it.

 

Thanks for the reply and help. I'm new to repairing (attempting) things on my own so I have some additional questions. Why do you think the combination switch is likely the issue for the washer motor but not necessarily the side mirror blinker? I'd think that since both issues are engaged by movements of the same stalk and going through the same switch behind the steering wheel. Why is the Front SAM (under the hood) a possible issue for the blinker? I'm not questioning your knowledge on the matter, I'm just trying to understand how these things work. I also remembered something new. As I said before, the side mirror flasher/blinker has not been working for like 5 years or so. During that time, I was looking around in the front fuse box (under the hood) and forgot to put the cover back on. Well, one day it was raining hard and I went through a giant puddle of water on the highway. After that, my dashboard was reading all sorts of error codes. When I got home, I sprayed used a hair dryer on it and sprayed some Walmart 91% alcohol on it. Once it dried, all the malfunction ( not working) messages disappeared and there were no further issues. However, after that, the side directional did work for about 20 minutes but quickly went back to not working and has been that way ever since. So maybe the fuse box/SAM water fiasco affected something. I say all this because it may help isolate my current issue. Lastly, If I got a new SAM unit, does it NEED to be programed? Can I try just cleaning the SAM first? ( so it would not need to be programed). One more tidbit of information. I saw something on Youtube about resetting car computers by disconnecting the battery. Well, I did, unhooked both cables from the battery for an hour and then put them back on. Needless to say, nothing happened aside from needing to reset the correct time on the dashboard clock.. Sorry for the ramble, as I said, I'm new to all this.