Hi all, I own a Mercedes Benz R500 and both rear and front wipers stopped working in same time. I already checked the fuses/relays/bonnet switch/replaced the stalk, but still not working. Please any ideas ?? thank you all in advance.

The front and rear windscreen wipers are controlled by separate components, but both are interconnected through the vehicle's SAM (Signal Actuation Module) system.

The front qipers are controlled by the Front SAM module. This communicates with the steering column switch and the wiper motor.

The rear windscreen wiper is controlled by the Rear SAM module, located near the rear compartment or under the back seat. This module handles the rear wiper and integrates with other rear systems.


Both SAM modules are connected to the vehicle's CAN (Controller Area Network) bus, allowing centralized communication and diagnostics. While they are separate modules, they work together to ensure synchronized operation when required, such as during rain-sensing automatic wiper activation.

If you have a MB specific scan tool, scan for codes. A problem with either SAM or the CAN Bus system will show up. That should be your starting point after fuses.

thank you for your notes.
now i have this warning showing in the photo attached

That symbol is to show you that your rear wiper is switched on.

Do you have a scan tool? You need to get your car scanned for fault codes. Until then, we'll be guessing.

Not sure where you’re located, but if it is below freezing right now, and you have any water in the system instead of windshield washer fluid, your pumps are frozen. Always make sure to get any water out before freezing temperatures because that’s a way to crack the pumps, the reservoir, the lines and the nozzles. Do not run your pumps if they are frozen. One way to check and see if this is the issue is by letting the car warm up and then seeing if the fluid runs after that.

Update on the riddle of sphinx.

Hi all.

- Checked both wiper motors externally and both work fine.

- Checked both motors plugs with circuit tester and it shows:

a. Front plug didn't show any power. b. Rear plug shows constant power of 13v.

- Checked rear fuses box with circuit tester and all shows right.

- Checked front fuses box with circuit tester and is all good except the front wiper motor fuse and relay (didn't show any power). I tried direct link in-between with a
piece of wire but it sparks every time I touched the fuse with other end. as in photo below



Then I pulled the entire front relays and fuses boxes out and part it out to check the inner component but it looks fine. not sure though because there might be some internal damage.

here are few photos attached below:


The only thing I haven't checked yet is the 4 plugs that plugged under this unit.
Also I would like to mention there are brand new and refurbished complete relays fuses boxes with same Part Number on eBay (as shown in the link below), but all Chinese made. do you think it might be any good ??
https://www.ebay.com/sch/i.html?_fro...00072&_sacat=0

thank you.

Have you scanned it yet?

You have not answered the question to your location. Do you experience below freezing temps? My Lx had this issue last week in the cold weather due to a tiny bit of water still left in the system from the summer. Waited for the engine to unfreeze the fluid and then added some winter washer fluid, and then all was/is good. The pumps can be tested with xentry, no need to rip modules apart….

just looking closely at pics: all soldered without visible bad joints.

The only this missing is conformal coating to prevent bridging between nearby opposite voltages.

Have you followed the chassis schematic to help understand circuits?

++++ Ok, now I've read this thread...
You've jumped the gun at dismantling everything to inspect without preliminary live testing.

A $150 scanner would may provide helpful fault codes
AND also let you activate wipers circuit by the SAM Controller.

Hi Baltistyle, I live in Sydney, Australia. very hot weather all seasons.

I scanned it it shows current fault:

-902A - The component for the signal wire to the component 'F58kB (Wiper ON/OFF replay)' has Short circuit to ground.
and
-9096 - The output of the component F4kR (terminal 15R) relay has short circuit to ground.

I scanned it it shows current fault:

-902A - The component for the signal wire to the component 'F58kB (Wiper ON/OFF replay)' has Short circuit to ground.
and
-9096 - The output of the component F4kR (terminal 15R) relay has short circuit to ground.

I scanned it it shows current fault:

-902A - The component for the signal wire to the component 'F58kB (Wiper ON/OFF replay)' has Short circuit to ground.
and
-9096 - The output of the component F4kR (terminal 15R) relay has short circuit to ground.

Those fault codes are either bad relays or a break in the wiring. Were you able to confirm power to the motors and the relay connections?

the electrician is already here.

I will see what comes up and update you.

Finally, all sorted.

Guys, if you wanna laugh, go ahead.

A failed relay in the rear fuse box was the issue.

Well at least now you know you're way around the electrics. How did you find it?

the electrician found it out.

the electrician found it out.
​​​​​​

UPDATE

Finally the car fixed. all was because of the front fuses/relays box. been replaced with a brand new one. Thank you all for your help.

Hello I’m having this same issue. So replacing the whole fuse box in the front engine bay is what fixed the issue? Nothing with the rear fuse box or rear relays?

ktory to dokładnie?

Most common cause is the switch in the hoos latches.. if it fails, the wipers won't work.