I got in touch with Stofferdavis, who had this to say via e-mail:
Quote:
| I did fix the problem and it turned out to be the micro switch in the front wiper motor. I ordered a new switch and installed it. If you don't want to go through all that, you can just replace the wiper motor. |
and
Quote:
| I remember bending the micro switch tab did work temporarily. The reason the wiper quits randomly is the module expects to see the signal from the micro switch every time the wiper parks. When it doesn't (from a faulty switch) the module thinks the wiper is blocked and stops it to protect the system. The part number is 61318353502 and it has to be soldered in just an fyi. |
Yesterday I pulled my wiper motor (you need a 1⅟16" socket for the big nuts on the shafts - I think that's 27mm). It's always annoying to pull the firewall trough out, but other than that, it wasn't a hard job. Reassembly involves some annoyance getting the two bracket screws started, but not too bad (the last guy in there had just not bothered, and left one screw in the trough).
My motor had been replaced at some point, and the linkage appeared to be in good condition.
Opening the motor drive (6 screws) revealed the microswitch, which is soldered to terminals that protrude through the plastic cover.
The grease was fresh and soft, and there was no interference with the operation of the switch.
I tested the switch repeatedly, and it seemed to work fine.
It is a SPST Normally Closed V4 Subminiature Snap-Action Switch with a Simulated Roller Lever.
It is a standardized size of 19.8x9.5x6.4mm, and the lever is 11mm long.
You can find switches like this all day with slightly longer 17mm levers for about $2-3, but I was unable to find one of these with a short lever, which means it is a bit of a "special." I wouldn't be surprised if a long-lever switch could be made to work, but I don't feel like making this my science experiment for the month.
The switch is in fact BMW Part #
61318353502, and is #5 in this picture from RealOEM:
I bent the switch arm up a little bit (not easy - didn't want to break it), and put it back together.
The wipers appear to work fine right now, but then again, they also worked fine just before I took it apart (they work fine when it's not raining...).
I will update this thread as I figure out whether this works, as as I fix it more...
- Eric