Rear wiper W210 - not usual faults

[bassbluestew]

At least not the usual faults I can find, having done a big old search.

Anyways, 1998 W210 E300td, rear wiper eratic sweep on pressing dashboard button. Wiper is parking randomly at various parts of the windscreen.

HOWEVER, when I press the wash function or it automatically comes on when the car is in reverse, it works fine !!

Now I'm assuming it's the same wiring carrying the signal for different functions to the wiper from the switch, but could it be there is a seperate wire for the once only wipe function ?? If this is the case, I will of course check at the rear hinge but any ideas on how to identify this particular wire ( colour ?? ) if it isn't obviously damaged.

Thoughts gratefully received,

S

 

[television]

I would have thought that it would be worthwhile to spray some switch cleaner into the dash switch, and try that first

 

[Myros]

having observed these things through the mirror

over the years, there have to be two relays controlling the action of the rww. The first one is its own relay, and the other is the relay for the front wiper. If you engage reverse with the front wiper on intermittent, then the rear wiper fires at the same time as the front. If you engage the rear wiper intermittently, and the front wiper intermittently, in D or N, then you will notice the rear wiper fires whenever it likes on its own frequency, and out of phase with the front. That's when it is under its own relay control.

As Malcolm says, try some switch cleaner first, as it could just be giving a "dirty" feed to the rear relay and confusing it, but be prepared to find and fix or replace the rear relay if that doesn't work. I'm sure we can find some part numbers if necessary.

 

[bassbluestew]

Many thanks folks...............now this is going to sound like a daft question too, I would normally use something like WD40, but
a) would that do ??
and
b) is there something better/more suitable ??

Thanks again,
S

 

[television]

Yes.. Maplins sell a good switch cleaner,,non drying. WD40 is a release agent and not good for long term electrics

 

[bassbluestew]

Thanks Malcolm, sound advice.

I'm offf to Maplins, anyone need anything ??

S

 

[highlander34]

how do you remove the rear wiper switch from the dash as my rear wiper does not work and want to try cleaning the switch first regards paul

 

[stanghetz]

Would appreciate some advise…..I appear to have developed an intermittent parking / not completing cycle fault with my rear wiper (W210), not dissimilar to the one described above. It appears to have started after driving through a very large puddle (or it could be just coincidental). My initial reaction was relay / park sensor etc. But that is probably a hangover from a fault with a non merc from many years ago.

Top of the list of questions is how to remove the switch, and the next is where are the relays located. Any other works of wisdom would be much appreciated.

Regards

StanG

 

[w210inSpain]

To remove the switch, first pull the radio out, you can leave plugs connected if it comes forward far enough. There are 2 screws at the top of the radio hole. Take these out and the wood will slide out. Then you will see the screws holding the switch in.

Please keep this thread going, I still have a fault with mine which I can´t fix. And would also like to know the location of the relay. (apart from the 5 pin relay attached to the motor housing)

Pete.

 

[Dec]

Pete, some of us aren’t familiar with the workings of the rear wiper, under what conditions does it operate;

Do the front wipers have to be on in order for the back wiper to operate?
Does the car need to be in reverse in order for the back wiper to operate?
Is there just one sweep of the rear blade or is it possible to have it on continuously?
Will a rear (working) wiper work if the tailgate is open?

Also, it shouldn’t be possible to move the rear wiper arm by hand, is this the case?

Sometimes when a wiper is turned on and the blade doesn’t move on the screen it is usually assumed that the motor isn’t running, this is not always the case, the motor could be running but not moving the blade. You might not hear the wiper motor running from the driver seat, even if the engine is off.
T o check this possibility, have someone listen for the motor running at the closed tailgate while the driver operates the rear wiper switch (ignition On, engine Off)

The only thing that I know about the relay is that on a C class like my own saloon, there is one relay type for the saloon and another type for the estate, I believe the one for the estate is incorporated inside the front wiper relay, so find the front relay and you have the rear wiper relay. I think it is called a K40 relay.

If you put your front wipers on to intermittent (engine off) and listen under the bonnet, near the fuse box, you may be able to hear the front wiper relay click every 5 seconds as the blade makes its sweep. It should be buried inside the fuse box, wherever that might be on your car.

Dec

 

[w210inSpain]

Thanks Dec,

It hasn´t worked since I bought the car, which makes it more difficult.

Neither the wiper nor the rear washer work, which makes me think it might be a relay.

I removed the inner trim to check the motor, and given a 12v feed the wiper does sweep the screen and park.

The only check I haven´t tried which I only learned from this thread is to try it with the front on intermittent and select reverse.

Thanks for the tip on the front relay, I´ll locate it at the weekend and see if it maybe that.

Pete.

 

[television]

Here is the circuit of the rear wiper

http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1997/E320/SYSTEM WIRING DIAGRAMS/6257.pdf

 

[e230 caine]

Hi,

I have a w210 with this rear wash problem too.. since owning the car.

If i press the rear wash wipe button nothing! yet If I press the front headlamp washer button this squirts water on the rear screen and then the wiper sweeps. (someone previously has swapped the wires around I think!)

I have checked the rear relay on the rear wiper motor which works fine.

I think the rear wash wipe button on the dash is at fault and maybe the problem on a lot of the w210's...

 

[television]

Have you checked out the wiring as on the link just above

 

[e230 caine]

Hey Up Malcom,

Ive just had a look, My e240 curciut looks different.

I had a look at the switch unit on the dash yesterday, it looks as though someone has simply spliced a blue wire going to the rear wash wipe (feed wire) to a (brown/yellow wire going to the headlamp washer system.

If I turn on the front wipers and select reverse the rear washa wipe doesnt work as it should.

Iam really intrigued in this fault and WILL get to the bottom of it.

So Front wash wipe works fine.

Rear wash wipe Relay tested ok & Motor works.

Rear wash wipe works if you press the headlamp washer button.

Headlamp wash system inop.

I need the wiring diagram for the e 240 1998 estate...Haynes??

Is it worth me thinking about a dash switch unit? Ebay? for Rear wash wipe switch?
Replace the wiring to factory?

Please Help!