Lights dimming and brightening

chasb said

Can this be a bad alternator or voltage regulator?

Lights all brighten up when you rev up and dim back down when the car idles.

Is the voltage regulator built into the alternator ?

Don;t wnat the battery to overcharge and blow up.

Any help here? Thanks

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Definitely NOT the voltage regulator.....it sounds like the alternator has weak output @ idle. I'd try a fresh higher output alternator. But before you do that, rev up your engine to 3000 RPM and check the current setup's voltage @ the battery. (all accessories off) That will tell you if your voltage regulator is bad......I think about 14.8 or so is around the highest you'd want. If your regulator allows the voltage to go higher than that, I'd say it's bad.