w208 horn not working

Page may contain affiliate links. Please see terms for details.
astamir

astamir

MB Enthusiast
Joined
Dec 21, 2011
Messages
1,237
Location
london
Car
w208 silver clk55
hi guys
help needed please
having a problem with horn on my w208 clk55 not working
checked all fuses checked the horns all seems ok
has anyone had this problem if so what was the solution on this please?
any tips would be very much appreciated and thanks in advance.
 
have you checked the relay? its in the sealed box next to the brake servo
 
markmifsud said:
have you checked the relay? its in the sealed box next to the brake servo
Click to expand...
opened that one but didnt know which one is for the horn if im not mistaken there 2 greens one blue and one black
do you know which one is for the horn and how to check it?
thanks
 
just checked the utube now and there one guy says its the steering angle sensor gone bad i have spareone i will try that one aswell tomorrow and post it here the outcome of that
 
Tried everything today changed the steering angle sensor replaced the relay with no luck
Any suggestions please?
What I'm missing ?
Thanks
 
The relay is changed with no luck anything else that can be a problem ?
Thanks
 
Good morning Astamir.
How are you with a testlamp?
While I don't know the specifics, the horn circuit on these is pretty basic, and If you have, or could get hold of a testlamp I'm pretty sure that I could guide you to either the actual fault or pretty close to it.

Edit: If anyone has any schematics, that would help.
Edit:edit - forget that - found a w202 one and it can't be that different.
 
Last edited:
Ted said:
Good morning Astamir. How are you with a testlamp? While I don't know the specifics, the horn circuit on these is pretty basic, and If you have, or could get hold of a testlamp I'm pretty sure that I could guide you to either the actual fault or pretty close to it. Edit: If anyone has any schematics, that would help. Edit:edit - forget that - found a w202 one and it can't be that different.
Click to expand...
Morning mate
Thank you very much for the help
What is a test lamp and where to get it from ?
Thanks again
 
it looks like a small screwdriver with a bulb in, and a lead with a clip.
The lead/clip go to a good earth point and the sharp probe is used to test for the presence of current.
Very easy to use and you can diagnose loads of electrical faults with one.
Halfords sell a cheapo one for a couple of quid, which should do the job nicely, or a really nice one for quite a bit more.

If you are happy probing into electrical connections and removing trim, I think that we could pinpoint your issue as it all looks straightforward (on the W202) to me.
 
View attachment 50341

Which one of these would do the job?
Btw I've got the one in the middle just a screwdriver with no wire but lamp inside
Thanks
 
Last edited:
What Dec said. Those are mains testers.
You need one specified for 12 volts (24 will do, but I prefer the 12 volt ones.)
Edit: It goes without saying that if you do get one, don't use it to test mains!!
 
Right!! That's the one.
First check it works - put the clip on a known good earth and the probe on the battery - tadaa! light!
Check the horn fuse (I know you have already. Clip on known good earth, you should be able to check that the fuse is ok - many fuses have a little bit in the top that you can just get the probe into. Don't forget ignition on!
Now, with the clip on a known good earth (I will say that a lot) see if you have anything to the horn. One wire will be brown, the other black with at least one tracer. That is the wire to check with the probe. shove the probe into the wire. Now press the horn. Bulb lights, then horn(s) are faulty or bad earth. Bulb doesn't light, no supply from the horn relay (could be because there is nothing to activate the relay but we will come to that.

Next bit follows while I look at the schematic...
 
OK, seemples.
First of all a linky to the w202 diagram I have. The 208 hopefully shouldn't be too different.
Linky
Check at the horn relay to see that you have...
Ignition live (shows this as pin 3 on the w202)
You can also check that the relay is working by listening to see if it clicks and putting the testlight on what is shown as pin 1 when you press the horn.

If there is no supply, I would suspect the fuse. If there is a supply and the relay clicks bit no output suspect the relay.

Now, assuming that you have a feed, you may be able to activate the relay with the testlight. push the probe into pin 4 and the light should come on dimly. It MAY activate the relay and cause the horn to blow. Careful - you WILL jump and hit your head on the bonnet.

Let me know how it goes to there and I can take you to the next stage.
Apologies, this has been written in a hurry, and I will be unavailable for the next couple of hours.

Remember a couple of things.
Ignition on!!
You can't damage anything by using the testlight.
The testlight should come on full brightness in all of the tests except where you use it to ground the relay coil.
Use simple logic and don't jump to conclusions.
The hard bit is access - in this circuit, the easy bit is the diagnostic.

Good luck - should be back around 18:30
 
Things to test.
Check at the horn relay, is it getting the trigger signal.
Is the relay getting 12v feed?
If no trigger signal then it could be the spiral spring that is housed under the airbag.

I think the process is similar to this.

If ignition is on, then power flows.
Press horn button, signal goes to the drivers side SAM where it triggers the horn relay. Horn relay then directly powers the two horns..
 
View attachment 50344

Ice got this at the relay if I'm doing all right
 
Last edited:
You must log in or register to reply here.

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)

Similar threads

K
Bi Xenon Projector Shutter
Replies
8
Views
695
kim 1091
K
T
Sliding doors
Replies
1
Views
396
m80
m80
W212Chris
Control Unit Not Responding - Autel
Replies
14
Views
1K
alexanderfoti
alexanderfoti
W212Chris
W212 Command Issues
Replies
2
Views
765
W212Chris
W212Chris
A
Left front door lights and soft close not working S 350 W221
Replies
3
Views
452
Riva811
Riva811
Back
Top Bottom