Viano brake light error

Whoa, sounds familiar! I had the exact same issue on my Vito. It was driving me nuts. The tail light would randomly go out and the dashboard lit up. Have you checked the switch itself? They can be pretty finicky. Sometimes it's just a loose connection. Is the error showing constantly or intermittently?

Where is the brake switch located exactly? Is it easy to get to?

Okay, so on mine, the brake switch was up under the dash, right above the brake pedal. A bit of a pain to get to, you basically have to contort yourself. But honestly, if you're not comfortable messing with the electricals, I'd suggest going to a workshop. A faulty brake switch can mess with the ABS and all sorts of other stuff.

Thanks for the info. Turns out I was accidentally hitting the brake pedal with my floor mat. I removed the mat and the problem disappeared. No repair cost!