It would be against the law for a motor manufacturer to fit a light which could cause the brakes to fail.
It is the brakes light switch
no
The brake pads are worn out and need to be replaced. The grinding sound means your brakes are about to stop working.
when the old ones stop working
Yes and any and all cars brakes get stiff or stop working when they wear out
A problem with your anti-lock braking system. Your brakes and your ABS are two different issues. Your ABS system keeps your brakes from locking when coming to a hard stop. If it is not working correctly your light will come on. Best to have a shop look at it.
If your bike brakes are not working properly, you should stop riding the bike immediately and have them inspected and repaired by a professional bike mechanic. Riding with faulty brakes can be dangerous and increase the risk of accidents.
Anything that brings the car to a complete stop? Such as the brakes or a Tree?
I step on brakes, dashboard light comes on which says stop.
It means there is a problem with the anti-lock braking system. If the light is on, The system is not working. What this means is that in an emergency panic stop where you stomp on the brakes, the front wheels will lock and the car will slide forward instead of coming to a safe controlled stop.
Brake Booster needs replaceing
If your electric bike brakes are not working properly, you should immediately stop riding the bike and have them inspected and repaired by a professional bike mechanic. Riding with faulty brakes can be dangerous and increase the risk of accidents.