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Car with electrical pulse

I have a '98 Ford Contour that seems to have a pulse. The electrical systems, (interior and headlights, heater,etc.) pulse like they aren’t getting an even charge. The battery light will flash on briefly every ten to twenty seconds.

It has a fairly new battery and cables, so I’m not sure where to go next. I first thought about the alternator going out, but it doesn’t really have problems with not enough power, only surges of too much.

Any thoughts?

Probably the voltage regulator (it is inside the alternator), or the wiring to the alternator. On many Fords, the engine computer sends commands to the regulator to adjust the output voltage to conditions, so it could be there too. Still, I would start with checking that all the wiring to the alternator is good and tight.

One cause of pulsing lights is from worn brushes in the alternator. If the brushes are worn to a point where the brush leads are now in contact with the slip ring of the alternator, the lights can pulse. Or if the brushes are worn to the point where the brush springs no longer provide enough force to hold the brushes to the slip ring, the brushes can bounce on and off the slip ring as it rotates causing the lights to pulse. Or the combination of these two conditions.


I agree with Tester. What you have described is more or less the classic symptom of worn brushes in the alternator. I would suggest that you replace it very soon, before it kills your fairly new battery and strands you in an inconvenient location.

You might be able to replace the brushes in this alternator for a lot less than replacing the alternator.