Headlights dim when brake pedal pressed...anyone else?

Antman said:
I'm comfortable with that.
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You just keep telling yourself that...

Anyway, personally I think they have always done that and you are just now noticing it. C'mon, mine do that (headlight instant flicker with 1st brake application) and I never noticed until you started this stupid thread lol. I am not concerned one bit. As a matter of fact, I wore one blue sock and one black sock today and I was 100% sure this morning they were both black.
 
Antman said:
I am wondering now if the alternator in the 4Runner just can't bring the battery back 100%...
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absolutely it cant. especially not from a severely discharged state. it was never designed to do that. a flat battery needs to be brought back to a full charge state with a trickle charger.

rigtec said:
(^^^LOL!) Ahhh, "That's Good"! So now we know/proved that the lighting circuit (brake light switch, harnesses and bulbs) are fine and have nothing to do with this symptom. We also know that the alternator has nothing to do w/ this cuz the problem still exsists with the engine/charging system removed from the equation!

"So now what"... :confused:
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MC/booster.

Antman said:
That's not correct- the lights do not dim unless the engine is running, no matter what..
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are you using a light meter? the lights get BRIGHTER when its running. so when they get dimmer, do they get dimmer...er than when its not running? did that make sense? it makes sense it my head, but once typed out....derp.

I don't think you can really trouble shoot this based on, "the lights get dimmer"

do you have a different KNOWN GOOD battery you can swap in?
 
nevada said:
absolutely it cant. especially not from a severely discharged state. it was never designed to do that. a flat battery needs to be brought back to a full charge state with a trickle charger.

MC/booster.

are you using a light meter? the lights get BRIGHTER when its running. so when they get dimmer, do they get dimmer...er than when its not running? did that make sense? it makes sense it my head, but once typed out....derp.

I don't think you can really trouble shoot this based on, "the lights get dimmer"

do you have a different KNOWN GOOD battery you can swap in?
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ALL GREAT POINTS!

I'll see what I can do from a battery standpoint...
 
Antman said:
What are you taking about?

I have an SR5 with the premium package. It came with factory heated leather seats, and all the other stuff.
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**MY BUILD THREAD HERE** (lots of MODS!) :madgrin: sorry being totally cryptic, it was meant as a compliment to all the cool things you've done.
 
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Like the OP, I Googled this issue and found the problem to be common on many makes/models.

In only one of the many threads I read was a solution found. Ground problem.

I think the HVAC analogy given above sums it all up.
 
My 2006 Tundra and my 2010 Tacoma both did this same thing from new, the lights would dim for a split second with the 1st brake application. It drove me nuts:help:
 
So I was curious about this too, now that is it dark out... a lot :wow:

Mine dim seemingly when the brake booster engages. I can depress the pedal slightly and it will not dim until it reaches a certain point, strictly empirical of course. It does it every time while I am at idle.

It does not do it when the engine is off OR it isn't noticeable because when the engine is off it is almost the lights are nearly same brightness as when they dim after depressing the brake pedal.
 
Just noticed this too on 14 LE in bumper to bumper traffic on way home in dark. Split second dim with brake application, then normal. Not every time. As was mentioned, it's likely the pull from brake booster. The "noticing" might have something to do with paltry amount of daylight we get this time of year ....
 
Antman said:
Funny you mentioned that. I have been doing research on this all over the web and pulled up exactly what you are talking about several times from Subaru owners/forums. It just bothers me that it just started happening...






I can barely post pictures that aren't mildly offensive, a video would probably crash the site :boom:

I am 100% certain this wasn't like this before- I drive to work in the dark every morning and pay attention to stuff like that- it's just the way I am, lol.
I do wonder how many others have this issue and don't hardly notice.

Me- it's driving me nutso.

Could be something to do with age/miles though- I still like your suggestion of a non-100% battery. I think that's possible...
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I have the same thing going on with my 4runner, seems more noticable to me when its cold out. (Could be my imagination)

I just stopped driving with the lights on to fix the issue........:redbrick:
 
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