Are you replacing the entire voltage regulator assembly. It screws onto the alternator and is replaceable with the alternator in the car. It has new regulator and brushes. I had mine rebuilt and all they did is solder in a new brush. The other brush failed a year later. I then replaced the whole assembly it has been fine since.. When the brushes stop making contact and the alternator stops charging you do not get a battery light because the brushes are part of the circuit that turns on the light. When voltage drops low enough you get an abs and srs light then soon after the engine stops running