GatoChulo

I've seen this question posted before, but didn't see any replies. I'll try my luck. Does anyone else's C5's headlights dim when any other accessories are used?? Ours dim when you 1.) put windows up or down, 2.) apply brakes to stop, 3.) adjust driver seat with power options.

Dealership says it's caused by "the load of all of the electronic equipment on the alternator system." I personally think they never had seen it!

PS. Any ideas on squeal? Start machine, any temp, any warm-up time, when initially placed in drive, engine comes down & squeals. Most noticeable in tight turn areas (parking garages, quite embarrassing!). At 11,000 miles, this machine should not do this.

98NassauBluC5

Well my '98 has a 527 watt amp with two 10's and everytime it hits, total "dimage" on the entire car. I think another alteranator or something might fix it. As for all other electrical things like the windows, same here. The car is a big electrical box.... I guess we need to just go with it, bro.

red97vette

ive noticed some dimming of my headlights randomly. I think its when the brake lights come on too. I guess too much load on the alternator or something...i donno. Im adding an amp and sub, so i think i might add a capacitor.



red

Rickk

I don't have this problem...Seems to me,,,if your headlights dim when an extra electrical load is applied, you either have an electrical problem, or your battery is weak..... Just my opinion.....

quick99ls1

mine does it too

JTAllen79

When I first got my 01' I had a very similar problem.My headlights would "blink" every time I applied the brakes.I also had erratic readings on voltage at the DIC but steady readings at the volt meter. Turned out to be both +/- battery connections were LOOSE by 3/4 of a turn. It was a new battery that had been replaced under warrenty at a Chevy dealer. As for the "squeel" I think you have an alternator bearing going south.

mrm1149

Now there's a dealer with a senior tech....can't manage battery terminals????

Grumpy

check the tensioner..Mine was making the squeel noise and was bad. My lights dim every mornig at almost the same spot on the interstate . Going up a hill, 5 minutes after leaving home.

JTAllen79

Exactly my point!

gunnygotavet

I posted this awhile ago and it seems its a common problem, mine dim when I hit the brakes.

Oldvetter

My headlights and dashlights used to dim, my battery terminals were loose.

vettecop1125

Mine dim from time to time.

WhiteC5Vette

Mine dim when I hit the brakes, but dim more if I close both windows at the same time. Common problem with most cars. Problem would be if they dim with no input from another electrical device. It is not that the generator can't handle the extra load, it is just a momentary problem caused by the regulator catching up to the sudden drop in current.

Edited to add information from three auto electrical engineers who gave me a fairly intelligent reply as to why, this happens on modern vehicles.
Under most circumstances, if the lights dim, then immediately brighten back up to normal when closing the window, or applying brakes, it is due to the regulator and not the generator. The regulator is designed not to switch to higher output too fast, or the engine could be overloaded. Therefore, there is a a momentary drop in the output with a large load, but the PCM will signal the regulator to ramp up the generator to supply more current for the extra load.
While driving and keeping the RPMs above 1000, the generator is supplying about 35 to 40 percent of its rated output. However, while driving the regulator can and will ramp up current from the generator almost instantaneously. At idle, RPMs below 1000, if the generator is signaled to ramp up current too fast, the engine will dog down (technical term for die).
A power window will draw almost 15 amps, while a rear defogger can pull almost 25 amps, same with the air pump. Headlamps and blower motor will draw 20 amps, while brake lights will vary depending upon their wattage ratings and the number of bulbs in the vehicle.
If a car has been sitting for a while and the battery is not fully charged, the dimming will be more noticeable.
Normal as long as the light flickers when a large load is suddenly applied such as windows, lights, etc. Not normal if they flicker while driving and no extra loads are suddenly applied, or small loads such as a radio are applied.

VetteramI

My 01 did it too. Worried about it right after I got it in 03. Had to change the battery this summer and the problem went away.

Frizzle86

well, for those looking for an improvement in their alternator. You could check out a company called Stinger. They take your factory alternator and make 100x better, used by a lot of ppl with systems.

Vetteman Jack

My headlights will dim on occasion when I use the window or seat controls. I think a lot has to do with how many other accessories are being used at the same time.

Sportsdude

I replaced my battery and now, no sign of dimming any more

NVTHIS

I upgraded to a 175 amp alternator and a Optima yellow top in my Pace Car, and it went away!

mqqn

Hi GatoChulo -

Both of my C5's have the electronic "impulse" disease.

When the ac compressor kicks on, light mometarily dim, windows operating = dimmer lights etc.

I have noticed the electric windows causing this on other cars than just vettes.

I have not had any issues with this, just something I noticed.

The only squealing I hear in my Z comes from the passenger seat...

best regards -

mqqn

Ragtop_Rob

Mine dim from time to time and have since I bought the car new with 3 miles on it.