Newbie with wiring issues

[2fattoofalloff]

Hi everyone this is my first post on here .
I have just bought a2007 ec250 and I love it but it has a few issues

1 , the digital display reads 419000 miles and total hours nearly 8000 , there is no way it's done this as it runs great and looks great .
2 no horn works although one is fitted
3 no brake light

I've had a quick look at the wiring and all looks ok but I'm no expert
Someone however has fitted heated grips ,

Any help would be great as I'm not much use at electrics

Thanks

[2fattoofalloff]

Sorted it now . Some cowboy had shorted the back brake out making the light stay on all the time