I am trying to fit a nice loud Mondeo dual horn into my Sei and though the plug fits I'm just getting a very muted click as if it's trying but not getting enough power or a bad earth. I've plugged it into my other spare Sei and it works perfectly.

Can anyone tell me which wire is the earth, black and white or purple? I'm guessing black and I can't reach the horn button and wiring with multimeter at the same time!

I'm thinking I can splice the earth with another wire straight onto a good earth point. There's no way I'm unraveling the loom it's connected to!

My standard horn actually works fine.

If I had another pair of hands I could sort this out quickly.

Ok I feel like a dunce now. My friend showed up and pressed the button for me while I messed about on the horn end. I think the body of the horn is the earth as when I hold it, it works but if it's hanging it doesn't, so I'm just about to make a bracket to hold it and see what happens.

Yeah it's all secure on a special one off custom fabricated bracket and it works champion! No more tepid little beep from my Sei.

I've done the same and got a mondeo horn on my sei (having some good fun annoying people with it as well lol), just wondering if when your car isn't running does your horn still sound? Also when it came to the bracket I managed to get the original bracket off the mondeo and rig it to my sei