The horn is located on the left side of the vehicle, below the nearside headlamp in front of the nearside chassis leg - you can just see it if you shine a torch through the grille in the bumper. To diagnose and rectify a fault with the horn push itself, you may need to remove the lower dash shroud in front of the driver (3 or 4 screws) and the steering column shroud (4 or 5 screws) so you can see around the steering column and below. The horn switch on the steering wheel earths the relay (although I didn't find the relay but I'm assuming there has to be one - it may be one of the ones under the fuse box, accessible by removing the passenger-side lower dash - I stopped looking for the relay when I found the fault elsewhere) - pull off the horn-push just by pulling and you'll see a red and blue wire (on my 51-plate van) that goes down to the slip-ring that allows a contact to be made while the steering wheel is turned. The wire from the slip-ring to the multi-plug is a different colour, however, and is black and white (on a 51-plate van). Unplug the multi-plug and, using a fly-lead connected to a good earth, lightly touch the white and black wire via the socket that's connected to the van's loom, not the bit of loom from the steering column (use a paperclip to avoid damaging anything) and you may well find that the horn works. If this is the case, it's most likely to be a dodgy slip-ring. You have two options: remove the steering wheel and replace the slip-ring; or, if you're in a hurry like me and your van is worth about £5.50, fit a push switch on the dashboard that earths the white and black wire when needed. I hope that helps.
Desaxe, October 2014
