My sidemirrors both left and right can't be controlled at all using the adjustment switches. They just stopped moving. Prior to this, they went haywire when the motors just kept on running even without pressing the adjustment button. Had to turn off the car to avoid burning them! Funny thing is when I go on reverse, the right side still goes on convenience mode wherein it tucks in a bit so I see more of the car's rear. Would that be a switch issue? If so, how bloody would it be to have it repaired? Thanks!

 

my passenger side sideview mirror is screwed up too
it doesnt go all the way to the memory setting...kind of annoying
but the manual controls still work

 

Yep, annoying indeed. Pretty embrassing riding a Merc then opening the windows to adjust the mirrors "manually". Right now, I just make sure I've got them proper prior to rolling out of the house!

 

haha thank god it hasnt come to that for me
worst case scenario i just got to use to switch to get it to where i want it
cuz the memory setting is berserk

 

There is no direct connection between the mirror position switch and selector buttons. The drivers controls are part of the headlight switch, and it communicates with the SAM on the CANbus. Each door has a module that listens to the SAM on the CANbus. The door modules have the drive electronics that move the mirror, operate the window, and the door locks.

Vehicles with memory seats have an additional wires from the mirror to the door module that reports the position of the mirror. The memory seat module uses this information to move the mirrors when the seat user moves the selector switch. If the seat module is getting bad information from the position sensors, it will not work properly in that regard, but would still work with the manual switch on the headlight switch assembly. A third player can also move the mirror on the passenger side. The transmission control module knows when you are in reverse, and can call a new position, and uses the door module to read the position sensor. The door module "puts it back"when you leave reverse. All the communication takes place over the CANbus, and the heavy lifting is done by the door modules.

One more wrinkle is folding mirrors. They are not available from MBUSA, but the rest of the world can get them. If the mirrors fold, there is a good chance that the wires from the position sensors in the mirrors is broken from the flexing of the harness.

Other wiring problems can be caused by water getting into the door and causing corrosion of the contacts to the door module. Corrosion inside the mirror housing is not unheard of in wet climates.

For NRN it sounds like his memory function is working, and the reverse function is ok. This would indicate good door modules and mirrors. The problem might be the headlight switch assembly. I assume the headlights work OK, so that would eliminate the CANbus and SAM from the most likely suspects list. It the switch assembly were PHP 500, I'd suggest just changing it, but since it is more like PHP 5,000, you might want to have a dealer verify it is bad.

For kevblah it sounds like a position sensor wiring or bad sensor itself in the mirror.

 

Moviela, many thanks for the leads. Will have the shop take a look at the switch assembly. Will be out to Singapore this weekend and will take a stab at it when I return!