w208 horn not working

[Dec]

That relay that’s removed looks a bit Green around the pins (corrosion?)

There is an identical black relay behind the Yellow one, borrow it, plug it in where you have the probe and then try the horn, with ignition on.

Dec

 

[astamir]

That relay that’s removed looks a bit Green around the pins (corrosion?)

There is an identical black relay behind the Yellow one, borrow it, plug it in where you have the probe and then try the horn, with ignition on.

Dec

i thought like that aswell and borrowed a fresh looking relay from a similar car replaced the relay nothing changed
if i understand it right the light on tester at the relay says ive got signal there please correct me if im wrong
where the signal goes from the relay does it go to horns straight away?
by the way tested the horns on the same car i borrowed the relay from the horns does work for sure.
ive got light in this two places at the relay.
the other question ive got will i get a light on testing the wires at the horns with ignition on without pressing the horn?

 

[Ted]

Light on at two points on the relay is good.
Now you need to put the clip on the POSITIVE side of the battery and push the probe into each of the other connectors. One should bring the light on - that will prove that the connection down to the horns is good. You can prove it by connecting one of the live connections to this one and the horn should blow.
The other wire will go to the horn push via the clock spring. Again, clip on the positive terminal and press the horn button the light should come on.
I'm starting to suspect the clock spring or a connector to it.

 

[Ted]

If the circuit is as shown the horn connector only becomes live when the horn button is pushed.

 

[astamir]

Light on at two points on the relay is good. Now you need to put the clip on the POSITIVE side of the battery and push the probe into each of the other connectors. One should bring the light on - that will prove that the connection down to the horns is good. You can prove it by connecting one of the live connections to this one and the horn should blow. The other wire will go to the horn push via the clock spring. Again, clip on the positive terminal and press the horn button the light should come on. I'm starting to suspect the clock spring or a connector to it.

I will go and swap the airbag with multifunction buttons and the steering angle sensor underneath the steering wheel from a similar car where horns are working

 

[astamir]

So if we have a light at these two points at the relay and horns are not blowing shouldn't the problem be between steering wheel and the relay?
And if the wires at the horn can't be tested without pressing the horn at the wheel I think the next step I must do is swap the air bag check it then swap the steering angle sensor and check it
Please correct me if I'm wrong
Thanks

 

[Ted]

The problem is probably between the wheel and the relay as there are more moving parts, but could still be between the relay and the horn.
You haven't proved that yet.

 

[astamir]

The problem is probably between the wheel and the relay as there are more moving parts, but could still be between the relay and the horn. You haven't proved that yet.

What do I need to prove it again please?
am I taking a wire from one of those live ports from relay place to horns?

 

[Dec]

Put a known good relay back in place, turn on ignition, get someone to blow the horn while you hold the relay, when the horn is blown you should be able to feel and hear the relay click each time the horn is blown.

Dec

 

[Ted]

What do I need to prove it again please? am I taking a wire from one of those live ports from relay place to horns?

See post at 18:41

 

[astamir]

I think I just killed the good relay ((((
I put it back on the car where I took it from and the horn doesn't work on that one as well and one of the front fans stays on but the horn was ok on that car before I took the relay out.
And I can't feel or hear anything clicking on relay when I press the horn

 

[markmifsud]

its not likely that the relay would have been killed by testing it this way, as has already been pointed out the connections do look a little green so maybe you have transferred some of the lose corrosion to the blades of the good relay.

where in London are you? your welcome to pop around here to see if we can work out whats not working

 

[Ted]

Just methodically go back over what you have done. I don't think you will have killed anything.
Good luck.

 

[astamir]

Now you need to put the clip on the POSITIVE side of the battery and push the probe into each of the other connectors.
Can you be more specific please about this as the battery on mine is in the boot and what connectors I should probe?
I put the relay back to the car where I took it from and the horn is dead on that car as well and one of the fans at the front stays on all the time now.
Looks like the relay dead but why and how I killed that one too I'm confused now(

 

[astamir]

its not likely that the relay would have been killed by testing it this way, as has already been pointed out the connections do look a little green so maybe you have transferred some of the lose corrosion to the blades of the good relay. where in London are you? your welcome to pop around here to see if we can work out whats not working

I'm North London Edmonton working in East London barking
Thanks

 

[markmifsud]

I'm North London Edmonton working in East London barking
Thanks

Well you lnow where I am if you fancy a trip to darkest SE London

 

[Ted]

Now you need to put the clip on the POSITIVE side of the battery and push the probe into each of the other connectors. Can you be more specific please about this as the battery on mine is in the boot and what connectors I should probe? I put the relay back to the car where I took it from and the horn is dead on that car as well and one of the fans at the front stays on all the time now. Looks like the relay dead but why and how I killed that one too I'm confused now(

Hi Astamir, this is a way of testing that there is a path to ground as opposed to a supply. If you can't pick up a supply easily this may be more difficult- I had forgotten the battery is in the boot, but there may be a positive supply post marked with a red 'plus' under the bonnet.
No matter - you have established that there is a supply to the relay and you have replaced the relay and it still doesn't click when you press the horn. This strongly suggests that it is in the circuit to the horn push and I would take the diagnosis there.
Tbh there are a couple of other checks that i would do to prove where the fault lay ( earth the relay winding and bypass the relay contacts) to help to prove the theory but it is hard to give advice when you are not actually there.
As for the issue on the other car - I would check the battery hasn't gone low, and possibly disconnect it for a few seconds to reset everything (you will need to reenter radio code etc), but I am wary of making the situation even worse.

 

[astamir]

Hi Astamir, this is a way of testing that there is a path to ground as opposed to a supply. If you can't pick up a supply easily this may be more difficult- I had forgotten the battery is in the boot, but there may be a positive supply post marked with a red 'plus' under the bonnet. No matter - you have established that there is a supply to the relay and you have replaced the relay and it still doesn't click when you press the horn. This strongly suggests that it is in the circuit to the horn push and I would take the diagnosis there. Tbh there are a couple of other checks that i would do to prove where the fault lay ( earth the relay winding and bypass the relay contacts) to help to prove the theory but it is hard to give advice when you are not actually there. As for the issue on the other car - I would check the battery hasn't gone low, and possibly disconnect it for a few seconds to reset everything (you will need to reenter radio code etc), but I am wary of making the situation even worse.

I can find the supplying wire its a red with white stripe
A bit dark at the mo but can do it tomorrow if you can describe the scenario with more details please like what do I plug to the supply wire and what goes where like

 

[astamir]

To the horn push you mean the problem likely between the steering wheel and the relay? Like the airbag or the steering angle sensor?
Thanks

 

[Ted]

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