The horn wont work - what to do?

I just bought a brand new horn from Mk1Autohaus_2003 on Ebay.

I installed it, but it won't give sound. I've checked the horn, and it works.
I have checked Haynes' wiring diagram, and it's correct. Also checked the fuze box layout here on the forum.

Does anyone know what could be the problem?

It's a 1975 fuze box

Do a search for 'horn' comes up a lot but mainly on later cars and twin horn setup on GTIs/GXs, would think if its all '75 wiring it will just be a bad connection somewhere.

I've tried spraying all the connections with WD40/CRC, but I guess I have to take out the fuze box and check it

have you checked the volts on the 12 and earth connectors?

With the mulitmeter?

yes or is you suck your fingers and hold each connector you should be ok.....joking, you sure the fuse is ok?

Ok, I'll try the finger thing! Lol

The fuse is ok, and it's in the 9th fuse place

check the Voltage mate, to me it seems to be the fuse, horns are basic so....FUSE lol. if you do try the finger test, can you get your missus to film it, so I can check you have done it right

Haha

Dunno about a series 1 but on my series 2 I took out the link on the fusebox and put in a relay and my horn has never worked so well!! they do draw ALOT of juice so maybe this is the problem also (if the same as a series 2) check the brown earth wire from the steering rack as this always gets manky… this is an eternal problem for mk1's!

Check the earth wire which is attached to the steering rack underneath the car,I've had probs with a bad connection on rack as the little screw becomes loose,worth a look if you havn't already.

Same for me. Brand new horn on the gti. Wouldnt work. Tried everything then realised the steering coloumn wasnt earthed. Ran new earth on steering rack and hey presto......a horn :-)