Hi all,

Got a problem thats making no sense to me..

My horn stopped working a while back, I swapped it with a known working one off the Tempra, but it still didnt work.

This afternoon I`ve looked at it again as the MOT is due.

I started by checking the fuses, for some reason the heated rear window one was blown (a 25a), as soon as I replaced it, it blew in my fingers.

I then took the horn off completely in case I`d put the wires on the wrong way, replaced the fuse & it didnt blow.

I`ve then reversed the horn wiring (one purple, one black with purple stripes), as soon as I connected them, the horn sounded perminantly...

I then disconnected the wires, got inside & then disconnected the horn button wires.

Went back under the bonnet & reconnected the wires... same thing, horn on permanently, despite there being no horn button in the circuit.. So I then reversed the wires & bang.. Fuse blew :bang:

Its had no electrical work done on it, nothings been added anywhere either.

I`ve never been so stumped by what should be such a simple circuit before!

In theory theres no point where the HRW is tied in with the horn circuit at all... I`ve got a mental block now!

I`m assuming the plain purple is the live feed & the black with purple stripes is an earth?

I`m also assuming the horns mounting bolt is an earth too?

Any help welcomed...

a73uk said:

I`m also assuming the horns mounting bolt is an earth too?

Click to expand...

Not to clued up on the Uno, but if like the mk2 Panda's of the same age the horn operated by a switched earth, so has a constant live, and pressing the button on the wheel earths it. Key information needed when fault finding on the wiring side of things

Most Easterly Pandas said:

Not to clued up on the Uno, but if like the mk2 Panda's of the same age the horn operated by a switched earth, so has a constant live, and pressing the button on the wheel earths it. Key information needed when fault finding on the wiring side of things

Click to expand...

Cheers MEPsta!

It would be nice to know if its earth switching, the 3 wiring diagrams I`ve got arent too clear on that, or the wiring colours!

I`ve knocked it on the head for today, hopefully I`ll have time over the weekend to look at it again (its Dads Wine making weekend as well, so I`ll probably be knee deep in grapes for most of it!).

Well, 2 months on I still havent got a horn, the MOT has run out & the tax is out next week..

Yesterday I fitted reconditioned front callipers (as one was binding), brake flexi hoses & front tyres (I got new discs too but the old ones turned out to be fine).

This morning I went out, dropped the fusebox & checked for any burning etc, nothing, its all like new, & no sign of water getting in, earths are all good, I put contact lube on ALL the connections before replacing them, just in case.

Just to reiterate, the heated rear window fuse is controlling the horn, the fuse was removed a couple on months ago (but the HRW still works?!?), & when you put a fuse in the horn sounds permanently...

I also took the column shroud off & disconnected all the connections, replaced the fuse, the horn sounded again, so its nothing to do with the horn button or a wire shorting around the column.

I then swapped horns with a known good one from my Tempra, did exactly the same thing...

Its driving me nuts! Helpppp! :bang:

After checking the my old (orange) haynes manual I saw that the grey relay on the left of the fusebox is the HRW relay, the space above it (which has a brass jumper on mine) is the space for a horn relay, so, I went out, swapped the HRW relay with a spare I had, put the fuse back in... horn came on again..

Removed the jumper from the horn relay space, put the fuse back in... horn came on again..

Replaced the jumper with the spare relay... put the fuse back in... horn came on again..

Oh, & now I`ve put a relay in, you can hear it click when you press the horn button.