Jaba wrote: Sun May 12, 2024 10:24 pm
Are you sure that it is the switch as it could be the horn or horns and the earth wiring to them under the front wing. I only know how to remove the switch on a Mk2 BX and it is a fairly easy job but if you have a Mk1 style of dash it looks to be more fiddly. Haynes might be a good bet for you.
Its online here:
https://www.mirari.fr/vVqv
It was the switch AND a poor earth under the wing. So double trouble!
Switch was quite deceptive as it passed all continuity and resistance tests but would not transmit enough current under load for horns to work. Non-serviceable swich was dismantled and serviced - quite bad arcing marks on contacts. Cleaned up and some silicone contact paste used to prevent corrosion. Ok now.
Twin horns, both capable of earthing through their brackets but neither was earthing correctly. Citroën fitted an earth cable between them - belt and braces in case of one bad earth but no good when two!

That kind on on-cost can't have been good for their relationship with PSA accountants!