Headlights dim - any ideas?

Thalass · Post by **Thalass** » Sun Feb 17, 2008 10:55 pm

I've noticed lately that when I put the brakes on, or something similar that loads up the electrical system, the headlights dim a bit. I've only noticed it when stopped at traffic lights, but I imagine it happens at other times, too.

Is this normal? Or a sign of a weak battery? Or weak alternator? The battery is only a year old and I've been checking the water levels on it fairly regularly. I know for certain that when the brake pump is working the lights dim, but I think it's also with other things like the aircon coming on and the power steering.

Oh, something unrelated but still annoying. Whenever it rains (ie: not for months untill last week) I get water in my tailgate-mounted lights. It's not a huge amount, it usually forms as condensation on the inside of the lense, but when I open the gate up I get a dribble of water out and when I take the lamps out there is a noticeable dribble, too. I wasn't too worried as it's summer, but after the recent rains here in WA I noticed that the lamps are starting to corrode, and I can't have that.

Where would the water be coming in? The lenses all look well sealed, and I can't spot any holes in the tailgate. I haven't taken the lining out, yet, but I guess I'll have to sooner or later.

Might be an excuse to try some LED replacement lamps, though.

subanator · Post by **subanator** » Sun Feb 17, 2008 11:04 pm

Sounds like a bad ground or neg cable. Check main ground terminals and connections for tightness and corrosion. See if this improves things.

AlpineRaven · Post by **AlpineRaven** » Mon Feb 18, 2008 5:48 am

Give a WD40 on the battery connections between starter motor, battery and ground...
Alternator should be charging around 14 volts while idling and if you're still unsure - go to a car battery place and get them to check it out with headlights on and off - should be no charge.
Cheers
AP

foxx510 · Post by **foxx510** » Thu Feb 21, 2008 1:26 pm

It's likely due to the poor headlight wiring, I noticed this too with mine, before I did this - showthread.php?t=8720

austcold · Post by **austcold** » Thu Feb 21, 2008 8:28 pm

You need a multi meter or voltage metre to check the battery voltage and then the supply at the lights, with the car running and the lights on, you need minimum 12v but it is possible to obtain the battery voltage level as 13v will give you a much better light

My battery holds 13.2v and gets 14v from the alternator when running, check this first.

Most cars get voltage drop issues with age usually poor connections than wires such as the off/on and dimmer switches, Relay's will defenately solve the issue but if your model is already fitted with relay's, cleaning connections may solve the problem without unesesary work.

Thalass · Post by **Thalass** » Fri Feb 22, 2008 8:44 pm

Augh. I guess I'll have to wait 'till next days off to have a good look, then. I'm elbows-deep in wiring enough at work as it is!

I'll have to swipe some stuff from work, too. Contact cleaner at least.

*edit*

I'm fairly certain that my model (1999) is wired up properly with relays and suchlike - to be honest I thought that was standard, but I'll have another look in the books at some point. Thanks!

BaronVonChickenPants · Post by **BaronVonChickenPants** » Fri Feb 22, 2008 9:27 pm

I'd say your two issues aren't as unrelated as you think.

With the lenses full of water it's almost like a short to the body when you hit the brakes and the lights come on.

Jordan.

Thalass · Post by **Thalass** » Fri Feb 22, 2008 9:47 pm

That's a good point... Though it did it thismorning and I don't think there was much more than a few drops of condensation on the lens at that time. But it doesn't take much. The brake/tail light (why there's only one in the tailgate when there's room for at least two (if not four) I don't know) is corroded in solid, so that might be leaking to earth a bit. Lucky the lighting on the outback is on the accessory bus, not the hot bus! I'd have killed the battery months ago.

stamp_licker · Post by **stamp_licker** » Sat Feb 23, 2008 11:14 am

Yes there's room for more lights look here http://offroadsubarus.com/index.php?opt ... ack+lights

Thalass · Post by **Thalass** » Sat Feb 23, 2008 2:19 pm

Odd... I go to register at that site, only to find out that my email address has been banned. I've never even heard of this site before!

Oh well.

robdddd · Post by **robdddd** » Sat Feb 23, 2008 8:34 pm

Not sure if there is any logic to the following, just noted your comment on checking the battery levels. over 20 years ago I stupidly topped up a battery to the brim, no air space at all and had a similar but much worse power loss. At night it was like driving by candle light and the wipers moved at snail pace, really wierd.

PS. I also get water in my outback lights, it is a real pain as it dripps out when the tail gate is up and lands inside the car!