Brake light not working.

My C800's brake light turns on only by pressing rear brake pedal. Front brake doesn't turn it on. Fuses were changed – every single one – but problem remained. Have anyone experienced the same issue? Thanks for your help.

sticky switch on the front brake lever? does it make a clicking sound when you pull the lever?

I'm not sure at the moment. Tommorow I'll check. I just remembered that horn not working too. Could it be related?

Open the switch and give it a spray of ACF50 or WD 40. Fixed mine and cost pennies to try.

I would re-check the fuses if the horn is out as well .... you might have a chaffed cable somewhere causing the problem. Otherwise, as Sim says, likely to be a sticking switch - worth stripping the switch housing down & cleaning out with WD40 or similar as Hmac advised.

QUICK UPDATE: There is "click" sound when pulling front brake lever. WD-40 not applied yet – I'm still at work now.

All fuses have been replaced by brand new ones.

Few days ago, horn made some very short ¼ second silenced beep when I pressed the button. Since then not even that.

Had a quick look at the wiring diagram - looks like the horn / front & rear brakes  / speedo, all work off the same fuse (sure someone will confirm/dispute that), so I'd be inclined to look elsewhere if the rear brake lights up & the speedo works.

 Pop a test light into the feed wire to make sure you're getting juice to the horn.  Then run a feed direct to the horn to make sure that's actually working.  Open the switchgear & have a look at the condition of the switch - they can fry.  If it looks dirty, spray some brake cleaner around the contacts.

I'd agree with the others, the brake side certainly sounds like the switch is gummed up - be a cheap fix.

Keep us updated with progress

Thank you all for you effort & valuable tips – the brake light does its job again!  I only cleaned the switch under the front brake lever and sprayed it by WD-40.

About the horn issue – I tried "the WD-40 hack" on a horn button. It was a quick action after work. I didn't have enough time to clean horn either to spray every connector relevant to it. Nevertheless, it started to make that silenced short sound again. Maybe it needs to be cleaned to, am I wrong?

You won't know for certain till you ascertained that the horn is working.  Once you know the horn's working, you can work your way back