Been checking around at small issues on my 1997 Discovery DP. Finally got dash air working. Found the LAST controller available in the world on ebay. Installed it and Dash air works perfectly. Installed new turn signal switch and now have turn signals. Happy about that. Now the horn. Hasn't worked since I bought the DP. Has to be solenoid or power to it. Haven't checked it but will this weekend. Steering wheel button seems like there is something missing under the rubber part. Seems Hollow when I push the button down. Most horns work off a ground but some people on here say there is 12v power to the solenoid. Is it constant 12v to solenoid then when I push button for horn, it grounds the solenoid? Not used to electric air horns. Most horns I've worked on were straight air. Another good thing, My frig has been on and working for 4 day, and is ice cold.......happy about that too.