I replace all belts with timing belt. My car has now 267,000 miles. All of a sudden alternator belt failed after 40,000 miles / 2 years

I can understand battery light on when belt fails but do not understand why brake light on dash should come on?

I checked brake fluid. OK. Checked free float in cap. OK

Is anything related to brake linked to alternator / AC belt?

 

when the electrical system fails, it throws everything off.
Did you fix the belt? did you reset the check engine light?

 

Surprisingly Check engine light is Not on. Only battery red light and brake red light on dash are on.

 

It's not uncommon for manufacturers to wire the brake warning light with the battery/alternator warning light so both warning lights come on when the alternator fails. That is because when the alternator stops charging, the car will eventually run out of electricity to run the engine. By the time the engine starts dying there won't be enough electricity to power additional warning lights to tell you to stop the car. Additional, when the engine is dying or stops running, the brake booster will stop functioning and defaults to a manual foot brake. Making stopping the car a much harder task and a lot more dangerous to stop the vehicle. Especially, if you're not aware of this scenario. Likewise, you would also loose power steering. So it's much safer to have the brake warning light come on when the alternator fails.

 

Thanks.
After repair I will find out whether belt failed for no reason or alternator failure caused brake to fail

There was no sign earlier like brake light on dash flickering etc before alternator failure. It was abrupt and little chirping belt noise and both lights came on