What would cause the headlights to sort of flicker or pulsate? They don't do it it rhythmically, just erratically. Connections are tight. Car has about 75K mi. on it, and orig. alternator, from what I can tell. Would the voltage regulator (internal to the alternator, right?) be causing this? Anybody have any ideas?

Headlight switch or high beam switch. Spray some Wd-40 or electric contact cleaner into them and see what happens. Hit the dimmer control also.

What would cause the headlights to sort of flicker or pulsate? They don't do it it rhythmically, just erratically. Connections are tight. Car has about 75K mi. on it, and orig. alternator, from what I can tell. Would the voltage regulator (internal to the alternator, right?) be causing this? Anybody have any ideas?

Thanks for the tip. One or two little hitches, though - as it is an `01, (and previous models probably had it too) the car has Daytime Running Lights (DRL) and Twilight Sentinel, so even though there is a headlight switch on the dash, it's kind of irrelevant - one rarely has occasion to use it. Do you really think trying to get at it to spray it w/ WD-40 would help? And the dimmer switch is, as I'm sure you know, integral to the turn signal (t/s) switch inside the column...

Yeah, my '97 is the same, that's why I thought about the switch. Switches that don't get used much get dirty, and if someone then tries to use it, it can get stuck in a bad contact position.

I didn't look at mine real close, but I assume you can still use the stick to get some WD into the column near the dimmer.

I don't know that this is where your problem is, but it's the cheapest and easiest place to start.

At first I thought about a bad diode bridge in the alternator, like you'd see on Fords alot, where the headlights would pulse regularly at idle, but you said random, which sound more like a bad contact/connection.

Two more things...

Do you hear any relay chatter with the flicker?

And does it do it if you turn the lights on manually at the switch?

"Cheap and easy" works for me for starters at least, that's for sure... And who in their right mind DOESN'T have WD-40 in the garage, anyway? As to the relay chatter, hadn't heard any of that... And I never thought to check to see if it happens with the headlamp switch in the full "on" position. I'll have to do that today. Thanks a lot for your time and effort in passing along the advice!

I was just curious....if the switch overriding the auto system makes it stop... would indicate the problem is in the auto control.

I always hear the little faint click when the sentinal turns them on, just wondered if that relay might be chattering. You'd hear it for sure, though.

Make sure you sensor is clean too, just to rule it out.

My Impala's lights used to freak out when a cigarette ash would get in the little well were the eye is...

OK - I'll definitely check that, too - that certainly qualifies in the, "cheap and easy" realm!