DIY: Fixing w124 wiper/defroster/blinkers problems
 

Not sure if this is worthy of a DIY...but this fixed my wiper problems that refused to work on the low setting. It was very intermittent, but very irritating as I didn't need the wipers going all the time in a drizzle of rain.

Thanks to vanweik over at mbworld for sending me in the direction.

Tools needed:

• 1x Philips Screwdriver
• 1x Small Flathead screwdriver
• Soldering Iron
• 10 Minutes of your time.

First find the culprit!

Multi-Purpose Relay/Combination Relay:
http://www.ps2cho.net/downloads/phot..._problems1.jpg

Remove the 6 screws...4 on the relay side, 2 below the fuses and remove cover. Remove from the relay from the slot...no tools needed.

http://www.ps2cho.net/downloads/phot..._problems4.jpg

Now you have it out:

http://www.ps2cho.net/downloads/phot..._problems3.jpg

Pop it open using the small flathead and look at the connections carefully.
On mine, you can see at the top right there were cracks and it didn't look a clean connection so using the soldering iron just touched it up.

http://www.ps2cho.net/downloads/phot..._problems2.jpg

Close her up...pop her back in and cross your fingers!

My wipers work perfectly now.

Alternatively, if this does not work, you can purchase a new one.
http://catalog.peachparts.com/

Hope this helps a few people if anybody comes across this problem.

I think folks will find that quite a few of these style modules fail for exactly the same reason. Bad/cracked solder joints are very common. I would pop open any such modular device and inspect it for bad solder joints before I went and replaced the unit.

Good post!

-tp

Glad to be of help ps2cho. I know that you've taken care of the problem now, but you could always install rain sensing wiper controls. I did last year and it is the best mod i have done to my car. I no longer have to fiddle with the wiper, it great on rainy days were the volume of rain keeps changing and your forced to keep changing the wiper setting. It was also very easy to install, only four wires to connect if i recall. I got mine on ebay for like $12 but here is the website of the company, http://www.raintracker.com/.

Interesting! Are instructions provided or did you have to figure stuff out?
Is there a model # that you could provide so I could keep my eyes open on ebay? :)

It came with instructions, you can access a pdf version on their website. It was very easy, all the wires that need to be accessed are behind the drivers knee bolster.

Just do a search on ebay for raintracker. There are three listed right now but all are listed at $79.00.

There are three models; RT-50, the original one which controls the wiper from intermediate thru high speed; the RT-50A, same as the RT-50 but with auto headlamp control and the RT-40A which controls intermediate thru low speed only. I have the RT-50 and it works very well. The new RT-50A is stated as having even better rain sensing optics then mine. There is a on-off switch that l mounted under the dash and I just leave it on most of the time. I may wire it so that it works like the Mercedes that have factory rain sensors so that it only works when the wiper switch is in the intermediate position for a more factory feel. Doing that would have taken to long when I was installing it as I was in a rush to leave for vacation and wanted it installed for the trip. It rained on me for a good 400 miles and the system worked great. My best friend drove my car and it stared raining, before he could ask how to turn on the wiper, the sensor activated the wiper. He thought that was the coolest thing he had ever seen. LOL

Here are the install instructions for our cars. http://www.raintracker.com/compatibility/mercedes-benz_c2_rt-50.htm