Hello,
I've got Volvo S40 2008 and the horn stopped working. So I've checked and there is power going into the horns.
If I remove the cable from one of it and connect it again the horn works only the first time and then stops again. Like something is making a fault to the circuit. Could it be that one of the two horns is gone and kind of breaks the circuit?
Is there a way ti bypass it? I've tried to disconnect any of them but then none works - I guess both cables should be plugged in so the circuit is closed.
I just want to try different things before start buying second-hand horns.
Many thanks

 

If you unplug 1 horn - the other should work (if good) They are not wired in series. There should only be power to the horn wires when you are pushing the horn buttons. (some earlier Volvos had power to the horns all the time, and the horn button grounded the horns)

There is a horn relay and fuse (#20) in the fusebox under the hood. If there's another relay with the same part number - you could simply swap to see if it's a relay problem. A shorted horn could have possibly damaged the relay -

 

Thanks a lot !!

It could be the relay. Will test it tomorrow.

The thing that baffles me is that when I put a multimeter into the horn sockets and press the horn I have a signal every time. It is weird that when I plug it back into the horn it only works the first time.

It is possible to have a bad ground connection somewhere?

 

What that's telling me is one of two things...

1) The circuit that powers the horn is flaky, and can't supply power to the horns for more than a short time. That could be a bad relay, wiring (hot or ground), connector or possibly horn itself.

or 2) You're not good at taking measurements. ;-)

I think "it's 1" though. ;-)

 

31/114 is supposed to be the ground. Try using just one horn to see if it will beep more than once.