Hi and thanks in advance! So my wife was driving home tonight and pressed the break or clutch pedal and the horn started sounding! first time only for a second then the 2nd time for about 20 seconds! 

earlier in the day she said the windows stopped working, passenger is now working but the drivers side only dropping slightly...

Any ideas? 1.5 tdci titanium x 2013 

Haha that's brilliant (well not really for you). It's a bit like the old top gear road trips. Me and a mate did this to another mate once on a camping trip lol.

It sounds like you might have a wire shorting out somewhere. I'd guess at your foot has pulled a wire out or the door loom has some insulation that's rubbed and eventually stripped. Time to crack the multimeter out and test the continuity on everything you've said is faulty. It's pretty hard to diagnose on the internet.

I'd check anywhere that the horn wires cross with the brake light wire first. Or test the horn wire to the brake light wire. If you have resistance then the short is on those two wires.

If something has stopped working then check the fuses. If they keep blowing then you'll have to find the short.

wondered if it could be an earth fault or BCM fault, I'm sure the door mirror failed to fold in a few times previously and the keyless entry didn't work around that time. maybe it was last winter. dodgy door loom connector would explain that but the horn... that's just out of top gear