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Horn Rewiring

Posted: Mon Dec 07, 2020 8:15 pm
by mickc
Does anyone have any experience of rewiring the horn please?

I changed the horn for a new one (works fine across the battery) but still silent when fitted, fuse #5 is good but still nothing. I had a look at the wiring under the bonnet but no joy there, dead. The wiring under the dash is a right mess with unidentified wires and relays everywhere for the cruise control/fan over-ride switch/fuel heater and all sorts of other stuff.

It really needs rewiring again from scratch but theres only 1 black wire from the horn button so I'm at a loss. Does the horn really need a relay? It only draws power for a second or two.

As you may have guessed, I'm no electrician and I don't want to pay hundreds for an auto electrician if I can avoid it.

TIA.

Re: Horn Rewiring

Posted: Mon Dec 07, 2020 10:41 pm
by g8dhe
It wise to have a relay its not the length of time but the current that the contacts have to break and the high voltage that is generated when the current is broken, most switches even if they could carry the current will flash over with the high voltages that can occur!

Re: Horn Rewiring

Posted: Tue Dec 08, 2020 12:02 am
by Bob
Re single black wire from horn button I think it's pretty normal for the horn to switch to earth.

Unless Geoff says different. :wink:

Re: Horn Rewiring

Posted: Tue Dec 08, 2020 10:10 am
by g8dhe
Indeed, earth is picked up from the shaft and the switch extends it when operated down the wire.

Re: Horn Rewiring

Posted: Tue Dec 08, 2020 9:59 pm
by mickc
Many thanks for the replies chaps, I think I'll leave it to the professionals, dig out my wallet and find an auto electrician.

Most of the mechanical stuff I can just about cope with but this is witchcraft to me.

Re: Horn Rewiring

Posted: Fri Jan 08, 2021 3:09 pm
by Ian
I'm spending my lockdown hours writing and revising various fact sheets. I'm writing a brand new one about the horn, and need to clarify an issue about the fuse. According to the list I have the horn is fuse number 5 (top row by driver knee, 5 from the left, red 10 amp) on pre-September 01 Bongos, but on later Bongos fuse 5 is reserved for the rear lights and the fuse for the horn is not listed. Any ideas?

Re: Horn Rewiring

Posted: Fri Jan 08, 2021 10:32 pm
by g8dhe
I've only got on the pre2001 diagrams so its the one you identified;
Image

There are only a few fuse changes post 2000 and I think they may have moved it into the X02, under the bonnet in the middle fuse box.