R129 Wipers/Turn Signal Control Unit

[Dec]

Hard to tell without pictures, is yours like below?

Dec

 

[Ardveen1]

R129 wiper stalk

Hi, thanks for the reply. It is not the same, I will take a photo tomorrow and post.

 

[Ardveen1]

R129 SL 320 Wiper Stalk - 1996 model

Hi Dec,

Tried to upload photo of wiper stalk I took this morning but am being asked to upload image to URL, I will need to look into this to see what the process is.

Frank

 

[Dec]

How to, see… http://www.mbclub.co.uk/forums/general-discussion/5721-howto-attach-pictures-post.html

Dec

 

[Dec]

Thanks for the pictures, all commutation is visual.

That stalk has over heated and the plastic has melted at the part with “bubbles” and that is what’s causing the fault.
Does it look like it can be dismantled some way, maybe to make a repair?

Dec

 

[Dec]

Not seen that type before
All you can do is try to dismantle it and clean it up and reassemble.
These things usually just pull apart and click back together.

If it can’t be repaired then only a new one will do, unless you are feeling luck in buying a used one from ebay.

Dec

 

[Ardveen1]

Hi Dec,

Thanks for the comments.

The brownish marks are actually grease which was on the inner casing. I cleaned this off tonight. This casing shows no signs of heat or slight burning. The two tabs near the grease marks push in when the block casing slides up to locate the casing. I can see a lower plate below the sliding speed adjuster and there is one above also. This adjuster moved about 150 degrees or so. There is maybe a wire feeding the upper plate to transfer power when the switch moves. I might try a multimeter on both plates to see if I can figure out the current process. The top part is now removed, spring loaded washer control. The next piece down is the adjuster speed mechanism, it will pry apart but I reckon it could be a mess to refix. I am not sure that this switch is the problem but know that it has to eliminated.
They can be picked up cheaply on ebay, I'd say new MB ones would be very pricey. I think that I will wait to hear the news from the member who offered to look at my original combo relay and maybe refit that if I receive good repair news.
The combo relay does sound like the most common cause and maybe the used one I purchased had the same issue, a bit coincidental I know.
The switch mechanism does look quite flimsy and I can see that it could be troublesome.
I wonder if with ignition on if i played with a wire connecting the upper plate to the lower could this initiate some wiper movement, what would be the worst outcome..blowing a fuse ?

 

[Ardveen1]

Dec,
the upper plate on the stalk controls the washer function, the spring loaded plate pushes down and makes contact which these plates to activate the washer. So the lower plate, below the slider speed control has the switching mechanism, not really accessible unless the top part dismantled. I think I will hold off on this until I have the combo relay totally ruled out. The search continues

 

[Dec]

It looked a bit like it was burned, there is one pictured below, before and after, which was burned so I thought yours had the same problem.

When the ignition is on, there will be 1 live wire, all the others are not live until the switch is rotated, rotating the switch will fed the other speeds as illustrated below, you would only touch any wire momentarily, if the wiper blade does a full sweep and returns to park then you have found the intermittent setting.

From the position of the rotating switch lever (bright White part) you should be able to work out which is intermittent.

You are unlikely to blow a fuse, But your wise to wait and see if the relay is at fault.

Dec

 

[Ardveen1]

Dec,

Thanks a mill for your help, your posts are very professional, not to mention your graphic displays.

I think I will hold off on the switch until the relay is totally discounted. There is what sounds like a click when position 1 is first selected. Fast works fine but blades stop wherever, At least there is something to clear the rain of the windscreen, and with the weather in the last few days it is a must.

If only there was a test for the relay to see if it is putting out the right voltages between the pins.

 

[Dec]

It’s wise to wait and see alright, better have some wipers for now.

Dec

 

[Ardveen1]

Hi, I got the wipers working on all speeds. Happy Days. It turned out to be the wiper motor. I removed the complete assembly, took out the motor and cleaneds the magnetic contacts on the stem of the armature, one magnet was quite stiff in its casing, with fine sandpaper and a compessor blowing air I cleaned it as best as I could, whikle leaving the magnets in place, just pulled back to allow clearance for strip of sandpaper. I reassembled the motor section and plugged it into the car and hey presto, it activated on all settings. I then re-asembled the entire and working pefectly since. Funny that it was the motor as it worked fine in fast but not slow or intermittant, possibly the current flow was not strong enough with the dirty / sticky motor.

 

[Carson218]

N10/2 Relay - R129 SL320 - 1996 model

Hi,

Interesting view of these relays. Alot of electronics contained within.

Further to last email, please disregard the bit about pulling back the tab with a screwdriver. The wiring connector block that receives the pins from the relay is housed within a sliding rail, this rail extends to about 2/3 the length of the relay casing, you simply push the inner end of the sliding rail towards car windscreen direction, this motion has the effect of lifting the wiring pin block up and it unlatches the complete assembly ( wiring connector block + sliding rail ) from the bottom of the relay. DO NOT remove the wiring block connector from the sliding rail mechanism by removing the rear small wrap around locking mechanism that fixes the pins into the connector block. I mistakenly did so and it is a pain to get them back in again. They are housed within a plastic grid so at least the wires did not get mixed up. Patience and inserting a small nail into each pocket until they all line up and pressed into the block and back on with the 3 sided wrap around locking rail and a bit of levering to prise it over the 4 small pins. Warning - no need for this so do not remove it.

My relay is the same as the bottom picture. The larger combination relay,I managed to get the top off but my numerous attemps at releasing the pcb base plate failed. An experienced member from another forum kindly offered to open it and check the solder so hopefully it may be repairable. ( €530 from MB Ireland to replace )

I did buy a replacement from Ebay before the repair offer arrived. I have fitted that but the very same issue arises. Fast wipers work fine. Slow and intermittant do not although they tried very slowly and moved a few inches and stopped. I can hear something click when I turn on wipers to first setting but still no movement in slow / intermittant. Could it be that the relay I purchased has the same issue. The seller sold it on the basis that it was working.

So now there is a few possibilities, maybe the relay is still the issue. Is there any way of testing the combination with a multimeter?. Could it be something else?. as the fast wiper works 100% I assume there is no issue with the wiper mechanism itself.

A bit disappointing thast the replacement did not work but hopefully I will get some good news from the generous repair offer. I would love to know if these is a test to evaluate these relays. There was one posted for the OVP on a W124 which helped my to get my E220 CE started.

Hi Ardveen1,

I’ve unfortunately just removed the wiring block connector in error trying to change the N10 relay, NIGHTMARE! Trying to line the pins up to the socket is tricky, I like your recommendation of using nails to guide them in, fingers crossed, thanks!