Headlights Dimming
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=14527
Printed Date: May 10, 2025 at 5:21 AM
Topic: Headlights Dimming
Posted By: GavinJuice
Subject: Headlights Dimming
Date Posted: June 05, 2003 at 11:01 PM
I have been having problems with my headlights dimming at an idle. The second i kick up the idle or accelerate, the lights brighten up. Also i had an elecrical problem before, my negative ground cable for my battery was sh*t so i bought a new one. I also bought a battery thinking that was the problem before i found out it was the ground. The battery was never being fully recharged. Could this possibly be a problem with my battery? Or this alternator related?
------------- ROCK AND ROLL!!
Replies:
Posted By: cpgoose
Date Posted: June 06, 2003 at 10:29 AM
Hmmm, in my experience, there are so many things that are related to this:
1. Battery
2. Small alternator
3. Small power cable for your amp
4. Maybe you need a capacitor
Well, this is assuming that you have some sort of audio
system, which you didn't really mention. For my problem,
I added a 1/2farad cap, and a larger wires for my amp's
power and ground. The wires helped a lot (I did them
first), and the cap seems to help somewhat. I still get
the dim if I'm at a light, but not as much. ALthough
I've heard my alternator is a weak one, so I'm sure that
doesn't help. I've heard, too, that if you do this too
much (dim), or put too much of a strain on your alternator,
then you run the risk of hurting it.
Posted By: cavyman
Date Posted: June 06, 2003 at 11:59 AM
If I was you I would think about getting a higher output alternator. What kind of car do u drive and how much power are you driving with amps and such? If you are running an amp or two, I would think about a new alternator. Do they stay dimmed or does it kinda go with the bass hits? We will need more info to get a good diagnosis.
------------- 1 plus 1 equals 2
Posted By: GavinJuice
Date Posted: June 06, 2003 at 2:04 PM
Ha Ha. I don't even have an audio system. I am just having the problem by itself. I guess i should have said that. Anyways this is an old cop car. So from what i have hear they have a larger alternator to run all the lights and all that other sh*t. This all happens simply at an idle.
------------- ROCK AND ROLL!!
Posted By: speedwayaudio1
Date Posted: June 06, 2003 at 2:17 PM
i would check all your wires comming off the batt. i would also run 1 or 2 extra ground wires from your batt to the chassis. what rpm is your idle set at? some ho alts don't start kicking the power untill 1000 rpms. check all that stuff before you spend money on a alt.
------------- Big Dave
Posted By: bberman1
Date Posted: June 06, 2003 at 6:50 PM
Could be a few things. But first off have you always had this problem or is it relatively new?
Posted By: GavinJuice
Date Posted: June 07, 2003 at 12:17 AM
I just got this car not too long ago, so i was wondering if some people could throw out some suggestions that i could try ------------- ROCK AND ROLL!!
Posted By: LittleBill
Date Posted: June 07, 2003 at 11:08 AM
some cars its normal, at idle my 93 subuaru lights dim, heaters slow down pretty much evertyhing drops, it also don't help my car idles at like 250-300 rpm, im dead serous it does, only thing u can do is may adjust the idle speed
Posted By: MAXST
Date Posted: June 07, 2003 at 8:04 PM
timing could be off. that happened to my friends mk3 supra. once we played with it, that stopped and power was up'ed alot. get baking soda and mix with water.. could be a corresion problem. to stop corrosion, get those little fuzzy rings that go around the terminal. that did the trick on my car. and check the connections. ------------- I need quality equipment, feel free to donate.
Posted By: dragracer
Date Posted: June 07, 2003 at 8:21 PM
you could also adjust the pully ratios on your car. all you would need is a smaller pulley on the alternator, and a new serpentine belt. you would also need to calculate what it would be doing at idle to get the right one. and if it revs really high you mught not be able to go as small as you want because the alternator can only handle so much. but first i would go to an auto supply store, and they will probably test you electrical system for free. they will tell you what wrong. make sure your battery has been fully charged before you go, if you want the right readings.
Posted By: Big Purds
Date Posted: June 08, 2003 at 10:15 AM
first thing to try would be to upgrade the charging wire from the alternator to the battery to something heavier (perhaps 4ga) and make the ground wire (the one you have already replaced at least that heavy if you used smaller wire...
second, run a new ground for the headlights out of a heavier gauge than already exists...probably even 8 ga would be nice...if you have this problem beyond doing these things, it may be time to look at a new alternator...
if you decide to go with a high output alternator, most of the decent ones will throw out a fairly high amperage even at idle...if you decide to go that route, contact me and I will let you know where you can get a really good HO alt for a reasonable price...
Posted By: GavinJuice
Date Posted: June 08, 2003 at 8:53 PM
Hey everyone thanx for the inquiries. I dunno what i would do without the12volt FORUM!!
------------- ROCK AND ROLL!!
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