got the hump over me horn

[billy_bunter]

The car (HC) failed iits MOT today on one thing the horn not working. On the one hand really pleased on the other annoyed as I cannot get he blooming thing to work. I have taken the horn off and run it straight of the battery and it works fine. I Then tested the +ve feed to the horn this is showing 0V when the shorted to earth and the horn switch depressed.

Is there a fuse/relay in this circuit?

he other thing to note is the indicator/horn is not functioning correctly and will not click/stay between high and low beam. Could this be the culprit? The wire colour at the horn is purple with a stripe. There are several purple wires at the bottom of the stalk.

Hope that lot made sense

[1972nail]

It will be the switch. Unless you feel confident stripping it down and cleaning the contacts you will be better replacing it.

[billy_bunter]

I will have a go during the week

Anything to 'watch out' for?

[droopsnoot]

Yes, when you take the top off the switch you'll see there are some springs holding the small ball-bearings that are used as conductors for the indicators - if you're not careful when you release the top, they'll fly off somewhere. As I recall it, the wire from the horn push is clamped in place and I've seen it broken off where it clamps.

[billy_bunter]

I got the unit off and did some poking around. The indicator unit is a Lucas one not a Vauxhall one. See pic of similar Lucas unit.
I took it into work today and had a good sniff around. The horn push when actuated creates a circuit correctly. I checked this by 'buzzing' through the circuit from the plug. Purple and brown (wire 9) and purple and black(wire 10). Thus I did not bother taking the unit apart.

Looking at the Haynes Circuit diagram wire 9 leads to a bulkhead conection at F4. This then goes to the Horn. The other connection goes to C4 on the bulkhead connection but there is no shown lead from this. I will buzz out/check vltages possibly tomorrow night and also see if I have a through connection from F4 to the horn in the engine bay.

Any other suggestions? Thoughts any welcome!

Lucas indicator/flasher unit. (I will upload a picture later)
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/ ... E/$_57.JPG

[droopsnoot]

The other connection goes to C4 on the bulkhead connection but there is no shown lead from this.

That's correct - if you look at the diagram of the bulkhead connector C3, C4 and C5 are all joined together and are a fused power supply from the battery, i.e. live all the time. So the current should flow from C4, along to the switch where pressing the button joins it to the other wire that comes back through F4 and out to the horn.

[billy_bunter]

What pratt did not check the fuses FIRST.



Found a modern'ish fuse in F1 which had broken. Took 3 out and put it into F1 all OK!

Thanks for you help gents

[billy_bunter]

As I have no spares. where can I get the fuses. I cannot find any at the usual supects around here.....

[droopsnoot]

Usually some on eBay. No help at all but there was a guy at several of the autojumbles last year selling these. Failing that you'll probably find some at the VBOA autojumble on March 1st if you can wait that long.

[billy_bunter]

thank you...