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Discussion Starter #1 (Edited)
Hello

I have spent some time this weekend fixing non-working wipers on a W203, C180. I thought i would share this experience.

The car had a SRS error on the cluster and the wipers did not work. Reading out the fault codes revealed that the child seat recognition sensor had a fault.

These cars have a sensor on one of the bonnet locks, if the bonnet is not locked or "locked" with bonnet open, then wipers and windows washing pump will not work.

In this case the windows washer pump did work when the bonnet lock was closed, but the wipers did not. There is a relay N10/1kM which gives 12v to Circuit 15R. The relay is controlled by the front SAM. The relay has 12v only when the ignition is on, but it is the SAM which decides when the relay is opened.

Circuit 15R provides 12v to several, amongst the relays N10/1kL and N10/1kQ which are the relays actuated by the SAM to control the wipers. Also 15R provides 12v to the child recognition sensor, SRS module, glove box light, cigarette plug and light, and the signal horn.

If all of these does not work probably the relay 15R (N10/1kM) have to be changed. The relay can easily be tested.

If a simultaneous error occur with both wipers and SRS involved, chances are that its relay N10/1kM (Relay 15R).

If windows washer pumps etc does not work, or if only parts of the wipers speeds works, then it is not a problem with relay 15R, (could be the column switch then)

Of course fuses have to be checked etc.

I have read quite many stories about SRS and wiper faults occuring at the same time and it is a pleasure to say that its down to relay 15 failing (and not SAM)

rgds
Oddemann
 

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Congratulations, Thanks for relating your experience here! You clearly know your way around the WIS circuit diagrams to have achieved this.:)

Did you investigate the relay N10/1 kM failure? Was it an open circuit coil or bad output contacts?
 

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Discussion Starter #3
The wire to the coil was loose on one of the connectors, we tried to solder the wire but it probably has been coated after fabric soldering. When we forced the relay closed with the hands the vipers where working and SRS error gone.

We used Star finder a lot, this tool is really good!

Oddeman
 

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My car has exactly the same symptoms. The technician said he had tried swapping the relay switch and that still didn't solve the issues. Can the SAM be partially malfunction?
 

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Discussion Starter #5
I belive the "technician" did not check the correct relay. If i remember correctly N10/1kM (Relay 15R) can not be fitted with the other relays, thats why we opened it to test it. Anyway, why did the so called technician not check if relay 15R gets voltage from the SAM ?

I dont believe the SAM is the problem. And i do not believe the technician is good enough :)

rgds
Oddemann
 

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Hello

I have spent some time this weekend fixing non-working wipers on a W203, C180. I thought i would share this experience.

The car had a SRS error on the cluster and the wipers did not work. Reading out the fault codes revealed that the child seat recognition sensor had a fault.

These cars have a sensor on one of the bonnet locks, if the bonnet is not locked or "locked" with bonnet open, then wipers and windows washing pump will not work.

In this case the windows washer pump did work when the bonnet lock was closed, but the wipers did not. There is a relay N10/1kM which gives 12v to Circuit 15R. The relay is controlled by the front SAM. The relay has 12v only when the ignition is on, but it is the SAM which decides when the relay is opened.

Circuit 15R provides 12v to several, amongst the relays N10/1kL and N10/1kQ which are the relays actuated by the SAM to control the wipers. Also 15R provides 12v to the child recognition sensor, SRS module, glove box light, cigarette plug and light, and the signal horn.

If all of these does not work probably the relay 15R (N10/1kM) have to be changed. The relay can easily be tested.

If a simultaneous error occur with both wipers and SRS involved, chances are that its relay N10/1kM (Relay 15R).

If windows washer pumps etc does not work, or if only parts of the wipers speeds works, then it is not a problem with relay 15R, (could be the column switch then)

Of course fuses have to be checked etc.

I have read quite many stories about SRS and wiper faults occuring at the same time and it is a pleasure to say that its down to relay 15 failing (and not SAM)

rgds
Oddemann
I have read the above, I have a C200 Kompressor 203 and has a peculiar habit. When you are at a high speed of over 40 KPH the horn, wipper and full light do not function, if you stop then accelerate they will work but only for a short time. Ihave not gotten the root cause of this.
 

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Hello

I have spent some time this weekend fixing non-working wipers on a W203, C180. I thought i would share this experience.

The car had a SRS error on the cluster and the wipers did not work. Reading out the fault codes revealed that the child seat recognition sensor had a fault.

These cars have a sensor on one of the bonnet locks, if the bonnet is not locked or "locked" with bonnet open, then wipers and windows washing pump will not work.

In this case the windows washer pump did work when the bonnet lock was closed, but the wipers did not. There is a relay N10/1kM which gives 12v to Circuit 15R. The relay is controlled by the front SAM. The relay has 12v only when the ignition is on, but it is the SAM which decides when the relay is opened.

Circuit 15R provides 12v to several, amongst the relays N10/1kL and N10/1kQ which are the relays actuated by the SAM to control the wipers. Also 15R provides 12v to the child recognition sensor, SRS module, glove box light, cigarette plug and light, and the signal horn.

If all of these does not work probably the relay 15R (N10/1kM) have to be changed. The relay can easily be tested.

If a simultaneous error occur with both wipers and SRS involved, chances are that its relay N10/1kM (Relay 15R).

If windows washer pumps etc does not work, or if only parts of the wipers speeds works, then it is not a problem with relay 15R, (could be the column switch then)

Of course fuses have to be checked etc.

I have read quite many stories about SRS and wiper faults occuring at the same time and it is a pleasure to say that its down to relay 15 failing (and not SAM)

rgds
Oddemann
Until this morning, I had a problem whereby the horn and wipers do not work, and in addition, the SRS warning light came on. All these problems occurred at the same time. The affected car is a W203 (2001) C220 CDI.

Replacing the N10/1kM relay (as suggested by oddemann) fixed all these problems.

Thanks to Oddemann for his suggestion.
 

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Hello, I'm having a very similar problem that I was hopinhvto get helps with.
I have a 2004 C32 AMG. I just bought it 2 weeks ago. When I got it, the SRS light was on on the dash and the seller told me it came on a year ago and hasn't caused him any issues so he never tried to get it fixed.
Since having the car a short time, I noticed the washer fluid pump wasn't doing anything when I pushed the lever in. I don't know how long it's been out because the seller never mentioned it and it was a few days before I tried to use it but the first try wasn't working. The wiper, however WERE working. Now, all of a sudden, the wipers aren't working either.
I asked a mechanic on Just Answers and he said it's probably the clock spring since the SRS light is on. I bought one and it just came in the mail today. I know how to replace it but before doing so, I wanted to do a little more investigation and then I came across this thread. Now, I don't k ow wheather I should try to replace it or just change the relay 15.
Is that what you fine folks would recommend first? That I change the relay before tackling the clock spring job?

Thanks in advance for any help I get.

Shawn
 

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I would not replace any SRS parts without a proper diagnosis, meaning pulling codes. In order to do that, you need a scanner that reads MBZ's proprietary systems. A generic OBDII scanner won't do that. Of course the dealer's SDS system will, and a less expensive option is iCarsoft i980.

As for tis problem, the clockspring would have nothing to do with the wipers as the combination switch sits behind that. The clockspring just manages the items on the steering wheel - horn, airbag and radio/menu buttons.
 

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Excellent find Oddemann, special thanks to you, your write up saved me from splashing 1k on trying replacing airbags.

I did exactly what Oddemann has said and fixed my symptoms. I had little difficulty finding the right one, but I am sharing my find (see the diagram attached). Also one mistake I did that as soon as I replaced the right relay, I tested and SRS/horn issues were fixed but wiper/wiper motor was stil not working, which disappointed me BUT I WAS testing with my hood /bonnet open, I found that as soon as I shut the hood/bonnet, the wipers/wiper motor was back to life.

Now I am not sure it is related but it started happening when a mechanic replaced my fuel pump and relay. The relay he put in was not a merc part. The moment it was changed, SRS passenger/horn/wipers stopped working. The mechanic tried to reset error codes but they were coming back immediately. In the end he said he will have to book an electrician and we may have to replace passenger seat sensor and/or airbags.
 

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Here's the front SAM relay diagram:

http://benzbits.com/w203/FrontRelays.pdf

The one you have labeled as "horn/siper/SRS" is Relay S, which is the starter relay. The other one labeled "Fuel Pump" is Relay M, and is for circuit 15R. That controls the horn, SRS, TeleAid and the cigar lighter.
 

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Sorry to pull this thread since it is very useful and I will bookmark this thread for next victim. I was desperated on this similar problem till I find this web and this thread initiated by Oddemann

Symtoms, SRS light on, radio/cigarette lighter not working, horn and wiper blade is not working

Oddemann, billion thanks on your work around and share this information. You save me many $ and also cure my stressful on this issue!!

Many of MB owner have to spend unnecessary parts replacement from inexperience technician. This is one of the case that my technician used Star to diagnose and said, either SRS module or seat occupancy sensor is faulty. I have some knowledge on wiring diagram, so, I asked him to check circuit and relay but he wouldn't do it due to work load. I decide to bring car back home

After use google and type key word "w203 SRS cigarette lighter wiper horn not working", I found this thread. After read this, I decide to diy but need more knowledge on using multimeter to inspect relay. I again search how to validate relay and how it works.

After remove relay on position M (p/n a0025422619) and check, it was not working! I head to the technician shop and borrow one from him. Before I plug in, i disconnect the battery (not sure necessary). After connect baterry after 5 minutes, Surprisingly, SRS light has gone. Radio and wiper and horn are back function.

I would say, my W203 Sport Coupe accumulated all the fault on this car. Problem we're from seat control is not working on the driver, seat control power leakage on passenger and cause baterry flat. HVAC flap is broken and cause noise when turn on Aircon, engine light P0171. Oil cooler was broken and water jam into automatic transmission house and need to overhaul. Etc....... So, whatever I saw the problems on others, it was on mine as well. So, try not to read problem any more.

At least, I learn how to fix car and learn how to use multi meter.

Thx Oddemann again for this valuable information
 

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Thanks a lot, Rodney. Great stuff! Beaut! Looks like I need to pull out relay "L" for the wipers and have a look at it. They all seem to be Tcherman Hella relays. Thanks for help.

Do you know if the relay "R" in your diagram (Terminal 87 relay, engine (N10/ikR) has any relation to the error: Relay circuit 87 (Engine P2505)?

Rather than cutting such relays open, is it possible to buy those Hella relays anywhere?

So many questions, so little time!
 

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Not sure about where you are, but those are fairly common relays and most auto parts stores carry replacements.
 

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Thanks Rodney for answer. I'm in Australia and when I enter "Hella" into Dr Google, HQ comes up, but I will try auto shops.

My relays and fuses are different to your sketch as mine is a C220 CDI W204 2007, but my question is: Is it OK to just pull out each relay and check the coil resistance or testing it with 12V? The key will not be in obviously.
 

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I see. So what should I do to fix the wipers issue? Should I try replacing the relays, or the control switch?
ปม
If the 3 incidents have been happened at the same time, strongly go with replacing relay solution.

If only one issue, eg. Airbag light, then, you should focus more on airbag and subsystem. For the airbag issue, mostly happened due to child occupant sensor which is located in the passenger seat.
 

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Thanks Rodney for answer. I'm in Australia and when I enter "Hella" into Dr Google, HQ comes up, but I will try auto shops.

My relays and fuses are different to your sketch as mine is a C220 CDI W204 2007, but my question is: Is it OK to just pull out each relay and check the coil resistance or testing it with 12V? The key will not be in obviously.
There should not be any problem if you just pull out. However, i would disconnect ground from baterry, just in case. Good luck
 
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