Wiper failed, indicators stopped, r129

[Garista]

1991 300SL r129. Hello;
I have been having problems with the wiper not working and now the indicators are also not working, the problem has been intermittent but now not. I have been following the advice on the blogs up to this point.

The lights are working and I recently installed a new febi combination stalk, which solved the no headlights problem which I had, but this is new. There is power to the wiper motor when the ignition is on and the wipers are switched on. I took apart and cleaned the wiper disk mechanism with the sweeping electrical arms which were all black and greasy. I also then cleaned inside the wiper electrical motor which was really filthy. It has carbon brushes which are ok. Then I bench tested it with 12V and it worked. I put it back in the car.

I cleaned and lubricated everything and tested it with ignition on, but although it is getting electricity to the wiper, the power seems to be too weak in the car to move it. In fact at the fuse it seems weak to begin with, not 12 V. The battery is good. Why not enough power at the fuse? This has stumped me a bit and I wonder if anyone has any advice.

 

[Garista]

By the way, the fuse connections are perfectly clean and shiny and the fuse is a good new copper one. Only fuse 11 and 12 have this problem. All the other fuses are strong. They used to work when the car was stopped before, so not speed sensitive I think.
I found quite a few others have had similar problems on Benzworld here:

Low voltage to fuse 11

My wipers wouldn't work, my headlight flasher wouldn't work and the washers also wouldn't work. Relay k26 buzzed loundly when I tried to operate the wipers. I checked fuse 11 and it was ok but the voltage to it was only 8 volts instead of 12 volts. I took out the fuse and put a good 12 volt...

www.benzworld.org

 

[Wearsafoxhat]

Could be the ignition switch itself. I think there are high current contacts in that wear with use.


Sent from my iPad using Tapatalk

 

[LostKiwi]

Sounds like you have a high resistance somewhere in either the feed to the motor or the earth.

 

[Garista]

Ok thanks.

Yes I was wondering about the ignition, the switch does seem a bit loose. I suppose that must come before the wiper fuse with the low voltage? It is actually only about 5 volts at the 11 and 12 fuses, but others are fine.

I've struggled to find all the earth points to clean them, but I will try harder. The wiper motor itself has an earth (I think) that grounds to the metal of the wiper, but it seems to me the whole wiper is separated from the rest of the car by rubber grommets (so not earthed?). A lot of the car has what is like white salts dusting around electrical parts though, because magnesium? So wouldn't be surprising to find a bad ground.

I went for a drive just now, goes fine and lights are working, but no indicators except fast when lights are on, realised I have a rear bulb out, so that may explain that mystery, I hope. Still no wipers, and no spray.

 

[mattkh]

,,,,,,, but no indicators except fast when lights are on, realised I have a rear bulb out,

The rear bulb which is 'out', is it one of the rear indicator bulbs..?

 

[LostKiwi]

Simplest way to check wiper earth is connect a direct link from wiper motor body to somewhere on the engine or a clean bare metal patch on the body.

 

[Garista]

The rear bulb which is 'out', is it one of the rear indicator bulbs..?

No, its the right rear light.

 

[Garista]

Simplest way to check wiper earth is connect a direct link from wiper motor body to somewhere on the engine or a clean bare metal patch on the body.

Ah ok thanks good idea, I will try tomorrow!

I found there's a main ground behind the instrument cluster. So I may check that after. I think I cleaned the one by the right front headlamp.

 

[davidsl500]

Dry joints in the N10 combination relay?

 

[Garista]

Dry joints in the N10 combination relay?

Hello, yeah thanks I did think of that but while I managed to open K26 wiper relay and clean I couldn't open that relay, but anyway the fuse seems to be before the relay and the wiper? But a bad ground could affect the whole circuit maybe?

So an update, this morning I started the car, it always starts first time, and the lights and indicators are all working. So weird. I was on the way to buying a bulb. Wipers still not working though I expect for the same reason. I' going to try a few things that have been suggested above.

(my ML is out of action too, I'm replacing the alternator and waiting for the new part. So I'm a bit stuck, also here in France you need all working, and it rains sometimes!)

 

[Garista]

One question: on the new combination stalk that I installed the holes for the little springs that I guessed were for the horn were a bit too big and the springs flopped about a bit (otherwise it is exact same part), I solved this by curling up some plastic into a tube and narrowing the holes, the horn works, but could this be a problem? There are two metal tracks on the back of the steering wheel that these two springs touch, is it just the horns? (I got fanfare horns, so 2! wowee). I would guess that this has nothing to do with the wipers...?

 

[Garista]

Update: just checked passenger side front ground. Found two wires under headlamp, one brown one black and green, the black and green one was broken and apart, the brown was furred up but I cleaned it. I twisted together the other one, difficult to access to do it properly at the moment. Don't know yet if it makes any difference.

 

[Garista]

OK!!! Not going to get too cocky about this but I think I found the culprit.

I thought about what was on the same circuit, as said I repaired the grounds and some broken wires, but then I decided I should check the cigar lighter. Well I had the lighter in it (not wise) but not in the on position, but under it was really dirty, so I took out the lighter part and vacuumed and cleaned it with contact cleaner. Then I decided to try the wiper again, and lo and behold! It parked itself!

I think it may have been the cigar lighter shorting. I hope so, fingers crossed. Need to wait and see how it goes.

 

[Garista]

Oh no! Still not working. Wiper parked itself then seems to have got stuck there. I definitely have more power on fuses 11 and 12 now though, nearly 10 volts. Maybe the wiper is stuck in a bad position... checking how to change that, I was able to move it by hand but now cannot. I can hear little blips when I activate the wiper, coming from the passenger side (LHD car) relays. Problem now may be mechanical or probably I am kidding myself.

 

[Garista]

OK on circuit fuse 11 and 12 there is 'comfort' stuff and I found the drivers sun-blind mirror cover is broken off and may be the light (?) in on position even though it is not lit up or duff bulb is shorting, so I put cover back on, not very well as it is part broken, but now I've got almost 11volts at fuses. But wiper still not working.

I touched 12 volts direct to the washer motor and it works fine and sprays.

 

[Garista]

It is as LostKiwi says, must be a bad ground somewhere. I used a battery to boost the power at the fuse while touching the neg to the engine, the ground was sparking a bit because a not very good connection and when it failed at the neg the wiper stopped, but otherwise worked fine and sprayed. So I have to find the bad ground somewhere. After a while of working it continued on its own, but after you turn off the ignition and on again it usually does not work. So some success...

 

[LostKiwi]

This has all the hallmarks of a bad connection.

Measuring a voltage is only half the story - it has to be able to deliver current under load too.
A test light is a valuable tool as it requires current and voltage.
Just an simple 21w brake light bulb in a holder makes a good test light.

 

[Garista]

This has all the hallmarks of a bad connection.

Measuring a voltage is only half the story - it has to be able to deliver current under load too.
A test light is a valuable tool as it requires current and voltage.
Just an simple 21w brake light bulb in a holder makes a good test light.

Yeah, actually I used both a test-light and a multimeter, it was the test-light that alerted me to the low volts. Anyway it is all working now, spray too, must have just needed some encouragement and all the grounds cleaned, in fact even the ABS light has gone out and stayed off. Not completely sure if it will last but it has for a couple of drives so far. I will still get at the ground behind the cluster though. I wonder if it is the computer updating?

I'm going to change the wiper blade, it is a bit too long.

By the way, do you know what the connected wires are that stick out of the spray tube by the little pump on the reservoir, should they be connected to anything?

And many thanks.

 

[Garista]

Oh and by the way just in case it helps anyone, I did spray a good amount of contact cleaner inside the ignition key slot.