E420 windshield wiper not working

[FranGuy]

Hi all,

Currently on the side of the road during a rain storm so this is a bit of a Hail Mary but here goes…

My windshield wiper is currently not coming on at all at any speed. If I press on the stalk I get fluid, but no wiper movement. I replaced fuse 2 as recommended by some other forums but that did not solve the issue. Any suggestions on next steps for troubleshooting would be great. Thinking it could be the relay, so if anyone knows how to test that, I’d appreciate it. If it’s the motor I’ll just have to wait until the rain stops…

Thanks!

 

[gsxr]

If the wiper had been working at normal speed prior to the failure, it's likely either the combo switch or the relay. I assume you tried all 3 speed settings. This isn't something you can troubleshoot on the side of the road beyond checking the fuse...

 

[FranGuy]

Thanks @gsxr! Yeah I had to wait for rain to stop…. Wasn’t too long.

Im troubleshooting today with tools and a garage. Tried all three speed settings and confirmed it doesn’t work on any of them. I order relay replacements when it stopped working so I’m guessing the best way to rule out the relay is just swap in a new one. Is there a diagram of the relays that I can consult somewhere? Also how would I rule out the switch?

As always believe how helpful this group is when it comes to diy stuff! Thanks all

 

[R129 UK]

Thanks @gsxr! Yeah I had to wait for rain to stop…. Wasn’t too long.

Im troubleshooting today with tools and a garage. Tried all three speed settings and confirmed it doesn’t work on any of them. I order relay replacements when it stopped working so I’m guessing the best way to rule out the relay is just swap in a new one. Is there a diagram of the relays that I can consult somewhere? Also how would I rule out the switch?

As always believe how helpful this group is when it comes to diy stuff! Thanks all

Try here, you might need to change the year as you didn't specify and I took a guess at '92:

Wiper Relay — 1992 Mercedes Benz 400E (124.034) V8-4.2L (119.975) Service Manual | Operation CHARM

Detailed repair manual for the 1992 Mercedes Benz 400E (124.034) V8-4.2L (119.975).

charm.li

 

[gsxr]

Schematics are in the FSM (link below). See printed page 159, PDF page 185... screenshot below also.

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD1/Program/ETM/ETM.pdf