Headlights dimming, just when i turn on my fogs Options

[goferris]

something i noticed on my car last night when i was driving. if i just have my headlights on it seems that they are brighter than when i have both them and my oem fogs on. has anyone else noticed that on their car? is there a relay or something that would cause that or do i just have a weak battery? nothing serious just something i would ask about.
also what is the bulb # on the silverstars for the lowbeams?
thanks guys

[coldbluesteel]

If your driving and they dim, it's probably your alt. Do you have a system in there?

[goferris]

If your driving and they dim, it's probably your alt. Do you have a system in there?

yeah but it is just a small one

[coldbluesteel]

Probably a weak alternator then.

[Gary]

How old is your battery?

[goferris]

How old is your battery?

8 mo is all. i noticed it before i got the sub though. it's not like they are way dim just a little bit. i want to put the silverstars in eventually since i don't have the cash for HID

[LewFX]

i got a spare alternator off my 99 for sale if u need one

[K-ESD]

the best way to tell if your alt. is on the way is when idling and you rev, your lights go brighter.

you can measure the running voltage of your alt. with a voltmeter, it should read 13.9V to 15.1V when engine is cold and 13.5V to 14.3V when hot. You can also measure the drop when you turn on your fog lights.

Another thing, how did you wire up your fog lights? If you use the headlight wire for power, this would be the reason why everything is going dim. That little wire can't handle the draw and causes a voltage drop when high current is trying to pass thru.

[goferris]

the best way to tell if your alt. is on the way is when idling and you rev, your lights go brighter.

you can measure the running voltage of your alt. with a voltmeter, it should read 13.9V to 15.1V when engine is cold and 13.5V to 14.3V when hot. You can also measure the drop when you turn on your fog lights.

Another thing, how did you wire up your fog lights? If you use the headlight wire for power, this would be the reason why everything is going dim. That little wire can't handle the draw and causes a voltage drop when high current is trying to pass thru.

they are stock fogs. and my lights don't get brighter if i rev in idle. they used to but that was because of a bad battery clamp not making a very good connection. but that was fixed months ago.
i don't know what it is. maybe it is just my eyes playing tricks on me. oh well. i am pretty sure it isn't the alternator.
oh well. nbd
thanks guys for your input.

[cnelson]

how much would a good alt. cost? jw..

[LewFX]

around 100 for rebuilt, used for 50, new is 150+

what about the start your car and then pull the negative cable off the battery, if she dies then your alternator is bad?

This post has been edited by LewFX: Jun 12, 2007 - 10:42 AM

[Daftboy]

my friend had this problem with his bonneville with a factory setup....everytime he would switch to the fogs or switch to highbeams the low ones would get slightly dimmer...What he did was run them on a stand alone switch without a relay...they now are crazy bright.

[topshed]

Could be a bad earth of course.

[Hanyo]

yea it sounds like a bad ground.

does your lights dim some more when you hit the brakes?

if your rev your engine and your lights don't get brighter, then its not a power/amp issue. There is something restricting the electricity from flowing. try to ground your fog lights directly to your battery.

that should solve your problem.