headlites/dashlights fade in/out

steviee7 · steviee7's Garage

I've been noticing my headlights and dashlights dim to about 95% and then back to normal. It seems to change the faster my engine goes, It's really not too noticable but it is and I don't know what it is. It doesn't do it all the time, It could start out fine and then do it and then go away, it could start out fading and then get better. Sometimes while it's doing it I can open the sunroof and the you can hear the sunroof motor change sounds in/out. Could it be the alternator, I know it must be electrical but where do I begin.
I hate when it's electrical.
One time while it was doing it I turned on my rear window defrost and it stopped doing it. I thought ahhhaaa, I found it! but then it did it again, with or without the defrost button.

Thanks

randywebb · 04-07-2005, 02:16 PM

may be Voltage reg

azasadny · azasadny's Garage

Alternator? Sure sounds like it to me...

FrayAdjacent911 · 04-07-2005, 02:23 PM

I'd say check your ground points... at the battery and engine/transmission. They could be pretty corroded.

Brother · 04-07-2005, 03:22 PM

I notice some similar behavior with my car. I have an aftermarket voltmeter on it as well and you can really see it happen. If I'm in a low idle with the lights on, they might dim. After about 1050 RPM, it is cured and the voltage will increase. I have an Optima which takes a little bit extra to recharge too. If it is low on charge, it will keep teh voltage at 12.5 until it comes back up to capacity at which time I'm seeing something north of 13V. I have never really gotten the 14V that most cars get. Don't know why.

350HP930 · 04-07-2005, 03:35 PM

If you have bad grounding or battery connections its possible to see the normal activity of the voltage regulator.

Joeaksa · 04-07-2005, 05:00 PM

Had my lights all seem normal, then would go bright for a bit. Turns out that it was a voltage regulator going tits up, and the voltage going up to 16+ volts! Not good.

Get a digital volt meter and put in on the car while driving. See what the readouts are then let us know. Should tell a lot...

JoeA

Tomahawk · 04-07-2005, 11:52 PM

I had that problem once but it went away when I changed the battery. How long since you last changed yours ?

randywebb · 04-08-2005, 10:15 AM

I agree - do the cheapest thing first -- clean up the tranny gnd strap at both ends and its attchment points.

Next - do the easiest thing - ne battery or at least a thorough test at a battery shop (no where else). i.e. test under load.

Next will prob. be new voltage regulator....