V40: Horn relay has no voltage

[ogmoreboy]

Horn on my recently acquired 2001 V40 1.9 D doesn't work. I have done everything suggested in this excellent forum but to no avail. Wiring looks good and tests for continuity, steering wheel switch (now) bright as a button, fuses and relays operational. I have now discovered that there is no voltage to the horn relay in the fuse box under the bonnet. Does anyone have any idea what to do next? Is there another fuse or relay in the circuit before the one under the lid? Maybe a loose wire - I just don't know.

[Clan]

Originally Posted by ogmoreboy

Horn on my recently acquired 2001 V40 1.9 D doesn't work. I have done everything suggested in this excellent forum but to no avail. Wiring looks good and tests for continuity, steering wheel switch (now) bright as a button, fuses and relays operational. I have now discovered that there is no voltage to the horn relay in the fuse box under the bonnet. Does anyone have any idea what to do next? Is there another fuse or relay in the circuit before the one under the lid? Maybe a loose wire - I just don't know.

The relay is fed by fuse 29 in the same fuse box , a 15 Amp fuse ...

[ogmoreboy]

Thanks Clan - I have just gone through a detailed wiring diagram and it looks like you're right. The problem remains that I can see no voltage on either side of the fuse. I just don't get it. Fuses either side show 12 volts but fuse 29 shows nothing. I can't understand how that can happen. Any ideas?

[Dancake]

There must be a break in the wire somewhere leading to the fuse, or a build up of rust on it somewhere. Unless fuse 29 is fed by another fused wire from somewhere, it's probably going to be a case of tracing the loom and checking for abnormalities.

[skyship007]

Originally Posted by ogmoreboy

Thanks Clan - I have just gone through a detailed wiring diagram and it looks like you're right. The problem remains that I can see no voltage on either side of the fuse. I just don't get it. Fuses either side show 12 volts but fuse 29 shows nothing. I can't understand how that can happen. Any ideas?

I would try the following:
1/ Put on best reading glasses and get some good light on the box.
2/ Pull out fuse and test, just because it looks good does not mean it is good, unless it's a real Volvo one (The number disappears when failed).
3/ Use a real good contact cleaner to spray the fuse sockets.
4/ Insert fully checked out old fuse, OR a real good new one.
5/ Give up and go find a branch from a nearby tree to whack the horn with!
6/ Go check the Earth is OK AND the other fuse box feed fuse.
7/ Get a bigger stick OR back to no 2!
8/ Check the Hailfrauds meter is set to 12v and not 240v.
9/ Back to no 2 again!
10/ Give up and find a good Indy auto sparks expert, as Volvo electrics are good, but some fuses, bulbs and even relays are not.

[Clan]

Originally Posted by ogmoreboy

Thanks Clan - I have just gone through a detailed wiring diagram and it looks like you're right. The problem remains that I can see no voltage on either side of the fuse. I just don't get it. Fuses either side show 12 volts but fuse 29 shows nothing. I can't understand how that can happen. Any ideas?

you have a faulty fuse box , have you taken the back off to see if you can spot anything ? Fuses 1 to 32 all share the same feed directly from the battery so you might be able to solder a thick wire from fuse 29 pin up behine the fuses to the common feed bar ... an easy repair i would think .. or find a replacement fuse box ...

[skyship007]

Originally Posted by ogmoreboy

Thanks Clan - I have just gone through a detailed wiring diagram and it looks like you're right. The problem remains that I can see no voltage on either side of the fuse. I just don't get it. Fuses either side show 12 volts but fuse 29 shows nothing. I can't understand how that can happen. Any ideas?

Are the fuse boxes showing corrosion ??

The engine box gets lifted to access the fuel filter on some models, so Clan might be right that the wire to the back is missing at one end or the other, although it's rare for that to happen. The wire would need to be badly corroded to not give a voltage response, so assuming it is an OEM fuse box, something has pulled out at the back is worth a quick light fused wire check. If you connect something up as a temporary bypass check, it's best that a fuse is included, just in case it causes a short.

Wrist watch and rings off time ??

[ogmoreboy]

Thanks guys. I'll get my old clothes on and have another go. I'll let you know how things work out.

[Gazzer83]

Just as a side one. Have you taken a supply to the horn to chack that it actually works. Be a shame to do all this work and the horn is U/S.

[ogmoreboy]

Got back to the car - 12 volts on the live side of 29! Put fuse in, 12 volts showing on horn relay socket, tested horn, nothing. Went back to fuse box and . . . no voltage on live side of 29! Close inspection shows that the live side contact on the 29 socket appears to have been pushed down. I have unbolted the fuse box, disconnected the main live wire and removed the base of the box. I can't see any way of fixing it without pulling out all the connectors and I don't fancy that unless it is really necessary.
I thought it might be possible to wedge something (a bit of an old connector of something) in the socket and cross my fingers.
What do you think?