w208 horn not working

[astamir]

Yes, between those two points. As I say, I like to be 100% but this is now pretty close.

The thing that confusing me now why there is a problem with the horn on the other where everything was good before I moved the relay plugged the relay on mine and put it back again
I disconnected the battery on that one to see if that will reset it
Quite busy tomorrow if I won't be too late I will try more tomorrow
Thank you very much for your help

 

[astamir]

Hi guys
Can you help me please to pinpoint the problem?
Thanks

 

[astamir]

View attachment 50383

So as I understand the closest supply wire would be from this duo valve red with yellow
Is that correct?
Thanks

 

[Ted]

Hiya.
Ok, given this a bit of thought as you don't have an easily accessible live.

You have established that with the relay out there are two connections that are live. This is correct.
The other two connections, one is to the horn, the other is to the horn push via the clock spring.
So carefully push a wire into one of the live connections and clip the testlight clip onto this. Make sure it is nowhere near the car body or other connectors.
Now push the probe into each of the other connectors. It should light up on one - that is the current flowing to earth through the horns. If you feel brave connect the live wire you have into this connector and the horn should blow.
In the other connector the light should come on when the horn button is pushed.
If it doesn't, this is the circuit you need to trace back through the clock spring and horn push.
Try these and post back with your findings.

 

[astamir]

Hi mate
Tried the way you explained in previous post nothing happened the horn didn't go off
I put a wire one by one both live points at the relay place clipped the negative clip on tester and put the tester in other two one by one but nothing happened.
((((

 

[Dec]

Try opening the relay, and then plug it in to test it by manually pressing the points closed with your finger.

Dec

 

[astamir]

Try opening the relay, and then plug it in to test it by manually pressing the points closed with your finger. Dec

This method worked It went off
It beeped
So if I understood it right now the problem is between the steering wheel and relay
What can I check next guys

 

[Dec]

It would seem your horn works so either the steering wheel or the front SAM is at fault, the steering wheel is less likely to be at fault and a bigger job to get at. So the front Sam can be lifted out, I think by removing the middle screw of 3 screws, on the fuse box, closest to the front of the car.

There are signs of water damage/corrosion with the Green stains on the relay so you should lift out the front SAM unit, its got a load of plugs, I think the are all idiot proof so each one will only fit back into its original slot, best to take a picture just in case. Where you go from there , I’m not sure whats next but you are looking for a bad electrical plug contact/corrosion.

Dec

Picture sources… w202 sam unit in Vehicle Parts and Accessories | eBay

Edit. I think removing the middle screw between the 2 Yellow arrows at bottom of picture will allow the SAM to “hinge“ lift out.

 

[astamir]

It would seem your horn works so either the steering wheel or the front SAM is at fault, the steering wheel is less likely to be at fault and a bigger job to get at. So the front Sam can be lifted out, I think by removing the middle screw of 3 screws, on the fuse box, closest to the front of the car. There are signs of water damage/corrosion with the Green stains on the relay so you should lift out the front SAM unit, its got a load of plugs, I think the are all idiot proof so each one will only fit back into its original slot, best to take a picture just in case. Where you go from there , I’m not sure whats next but you are looking for a bad electrical plug contact/corrosion. Dec Picture sources… w202 sam unit in Vehicle Parts and Accessories | eBay Edit. I think removing the middle screw between the 2 Yellow arrows at bottom of picture will allow the SAM to “hinge“ lift out.

Do you think the contact cleaner would help?

 

[Dec]

Yes contact cleaner will help, the long flat part of the SAM has a circuit board so that might be worth looking at if you can figure out how to open it.

Dec

 

[astamir]

Yes contact cleaner will help, the long flat part of the SAM has a circuit board so that might be worth looking at if you can figure out how to open it. Dec

What if I just spray it in contact places at the relay port?

 

[Dec]

I don’t think you can get at it properly like that, you are just relying on a lucky fix, you might need to unplug some of the connections to the underside of the relay tray and have a proper look. We don’t know for sure what’s up its all guess work at this stage.

Dec

 

[astamir]

I've got aSAM unit I will try it later on today and update here

 

[Dec]

How the SAM comes out, as described in post #48 is not correct.

Dec

 

[astamir]

How the SAM comes out, as described in post #48 is not correct. Dec

Yah as you said you take the screw in the middle on the fuse side
The fuse side pops up and then theSAM unit
I will try to put the unit in today later on without contact cleaning

 

[astamir]

SORTED!!!!
Can't thank you enough guys
And a special one dec
Replaced the SAM unit and now if you hear someone beeping in north London its me))))

 

[Dec]

Good result, did you notice anything on the old SAM that might have caused the fault?

Dec

 

[Ted]

Great stuff - and another thanks to Dec - I wouldn't have suspected the SAM - I was starting to think it was between the relay and the horn push.
Glad it is sorted.

 

[astamir]

Good result, did you notice anything on the old SAM that might have caused the fault? Dec

No nothing mate
The only thing I noticed after I changed and was transferring the relays to the new SAM the next to the black green relay had more corrosives more than the horn relay in one of my pictures

 

[Dec]

It has a PCB so that's probably has some corrosion too.

Dec