Why would headlights come on when you brake Ford Fiesta?

Answer 1

a common fault on some Ford is that the earthing points for the electrical system corrode, and cause a bad earth. this can play havock with the light etc. Try cleaning them up. they are usually postioned on the

* front - inside the engine bay on the left an right hand sides, behind the headlights * rear, somehwre around the rear lights. An easy way to tell if this is your problem would be to get another person to stand behind the car, and put the side lights on, indicators and brake lights at the same time, you may find that all the light go mental, in which case it is your earths!

Answer 2

Well when you are driving the alternator is at a constant speed then when you slow down the alternator sort of skips a beat causing the lights to dim!