Windshield wipers stopped

[rutger kohler]

Hi, my wife stuck a foreign charger into the cigar lighter and blew the No2 fuse, which powers the wipers amongst other items.  I renewed the fuse and everthing else now works on the No 2 fuse except the wipers.  I have got the wiring diagram and can fault find my way aroud the wiper circuit but wondered if someone can suggest where to look first.  Could the wiper relay be fried?

[al_lieffring]

First a warning, always make sure the Ignition switch is OFF anytime the wiper motor or linkage is being worked on. it can start rotating without warning and cause injury.

The first thing I would recommend would  be to unbolt the wiper arm linkage (under the dash behind the glove box) there is a 6mm bolt that splits the linkage in two. Then turn on the ignition and switch on the motor and see if it rotates.

If not, start checking the electrical circuits and relays.

If the Motor does turn the wiper shafts are corroded to where the shafts no longer rotate in the bushings.
I posted a tutorial on wiper shaft servicing many years ago it might still be found in the tech manual section.

Good Luck.

[Paul & Dolly]

Hi Rutger,

I would start at the relay, and check that you get a (+) from the fuse, and the correct signals from the steering column stalk, when operated.

Hope you sort it out

Paul

[ja17]

Could be the relay. Double check and twist all fuses.

[rutger kohler]

Hi, thanks for the replies, first to Al, thanks for the tip about disengaging the wiper mechanism, however I do think my problem is electrical.

To Paul, thanks for the blown up view of the relay and wiper motor connections, currently loolkng at the relay connection. 

And to Joe, have replaced the fuse thanks and the horn works fine (also off fuse 2) so looking further downstream at this point

[rutger kohler]

Have just checked the plug that feeds the wiper relay and no power on pin socket 56b (or any other one) when ignition is on, and horn works ok, so I am thinking something wrong with the wiper lead off Fuse 2. Is it possible to ease the fuse panel off the firewall and have enough give in the wires to look behind it. Would be great not to have to get under the dash looking for problems.

[Paul & Dolly]

Rutger

Be a bit cautious here, as  the wireing diagrams show the (+) as going to 56b, and this is true for LHD cars, but I know of two RHD cars that the (+) went to 56, this was certainly the case on my RHD 250SL. That is not a problem usually, but I had installed a solid state "Relay" which required the (+) on 56b, so I swopped the pins over in the plug.

It is relativly easy to check , as one pin goes to Fuse 2,and motor  pin 4,  and the other pin goes to the multi function switch 29e and motor pin 1.
Sometimes there is only one wire on relay pin 56b as motor pin 4 can come straight from fuse 2.

I would establish which way yours is wired and then test with a "jumper" from fuse 2 to the correct relay pin.

Hope this is useful

Paul

[rutger kohler]

Only working on this for a short time each night but I can confirm that the 12V comes in on socket 56, at the plug to the relay

Bench tested the relay with 2 x12V supplies, one on pin 86 and earthed on pin 85, and one on pin 56 and earthed on pin 56b.  by touching the supply to pin 86 and off again, feed connects off and on to pin 56b from pin 56 so relay ok.

I reconnected the relay to the plug and with the ignition on the windscreen wipers go, but won't switch off (suspect that's the way I left the relay set).  After removing the relay plug again, cannot get a 12V feed from plug socket 86 when cycling the steering column windscreen wiper switch off and on, so now suspect problem lies either in the steering column windscreen wiper switch or between here and fuse 2.

From my take on the wiring schematic, if I unplug the steering column master plug and socket under the dash, I should be able to get a 12V feed off pin socket 80, with the ignition on.  Do you agree?

[Paul & Dolly]

Hi Rutger,

I made this drawing a few years ago, and mine is a 250 SL (early version) so it may or may not help ! as I know there are some physical differences between the early and later column multi function switches.
Interesting that your RHD also has the + going to 56
The good news seems to be your relay works ok, and the wiper motor can run.

The motor needs a supply on 4 (from fuse 2 directly or from relay pin ) to enable self parking.

You should be able to test most things from the multi pin connector under the dash - there are two down there, so check you hace the correct one, or things get very confusing.

The column wiper switch only provides a momentary signal, and then the Relay  coil "Holds On" until it receives another momentay signal from the column wiper switch then it drops.

Good luck.