Skip to content
View in the app

A better way to browse. Learn more.

Ultimate Subaru Message Board

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

headlights dim at idle

Featured Replies

i had the buggy (89 gl-10 t-wagon) out for a spin this weekend. my headlights are pretty crap when im idling ~800 rpm iirc. when i start to move they get brighter. didnt see anything in the USRM or my searches. is my alternator dying?

is my alternator dying?

 

Most likely, or the belt could be loose. Check the alt for AC output - it should be zero. Probably the rectifier is going on it.

 

GD

the voltage regulator is toast...the brightnes?>volts go up as revs get higher.

 

. after you replace your alt, it would be a good idea to install a volt gauge. being as your digi dash doesn't have one.

sometimes just the wiring or connections at the alternator, headlights or battery are to blame aren't they?

Yes, poor connections in the charging circuit will cause the the battery to have less charge than it should have and so this kind of thing happens. A small amount of dimming at idle is pretty normal. As was stated, a loose alternator belt will also cause this to happen. When diodes fail, usually the warning lights in the alternator circuit will glow dimmly.

to confirm everyone's words, yes, you probably need a new alt, or battery, or both. my alt pooped out several months back and i got a friend who fixes electric motors for a living to repair the diodes. and yes, the idiot lights glowed dimly at idle. first off they were REALLY bright, then eventually faded as time went on. i'm not positive what he fixed but the alt works fine now and the cost of a free repair beats the $110 for a new or $25 from the j/y, self pulled.

 

battery cables could be the culprit as well. a bit of sandpaper or wire brush will clean them terminals up nicely.

  • Author
after you replace your alt, it would be a good idea to install a volt gauge. being as your digi dash doesn't have one.

 

i have a voltmeter already installed :banana:

 

if im gonna replace the alt, guess i should look into upgrades, huh?

cool beans..wouldn't want to damage your digi cluster up with 18v spikes:lol: .

 

there was a thread that went un-noticed with some great info! ,antoher alt swap choice. older v6 maxima (90a)..bolts in, just need to change the pulleys & plug.

 

heres the link

http://www.ultimatesubaru.org/forum/showthread.php?t=44094&highlight=maxima

 

its what my next alt will be:headbang: .

cool beans..wouldn't want to damage your digi cluster up with 18v spikes:lol: .

 

there was a thread that went un-noticed with some great info! ,antoher alt swap choice. older v6 maxima (90a)..bolts in, just need to change the pulleys & plug.

 

heres the link

http://www.ultimatesubaru.org/forum/showthread.php?t=44094&highlight=maxima

 

its what my next alt will be:headbang: .

Dude, that is freaking cool beans info on that Maxima alt. I may have to get one for my XT Turbo. The XT Turbo's alt even has a single belt 4 groove pulley on it... so that'd mean the stock pulley *should* work. That'll be freaking sweet if its just a direct replacement.

  • Author
Most likely, or the belt could be loose.

 

i hate asking stupid questions like this...

 

if the belt is loose, is it going to squeal and make a bunch of noise, or can it be somewhat quiet and loose? last time i messed with the accessory belt i used my breaker bar to pull the alt and put tension back on the belt.

Please sign in to comment

You will be able to leave a comment after signing in

Sign In Now

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.