My headlights dim a little when I press the brake. I figured it was the alternator or battery but both checked out good at the auto parts store. Any suggestions or similar experiences?

 

My car has always done it, and I have had the same battery for the last 2 years, so I don't think its the alternator or battery.

 

Check your grounds..........there are a few in the engine bay itself and i believe a few more under the dash on the driver side and behind the drivers left foot kick panel.

 

are you saying the grounds may be loose? if they were disconnected they wouldn't work at all, right?

 

loose is an option but corrosion is another. ever see that green or white stuff that builds up by your battery ? that reduces the effective connection therefore killing its efficiency. just take a look for corrosion around the grounds and clean up with a wire brush. hey its a starting point. if your sure they are good then let us know and we can take it fron there.

 

there was a massive grounds thread once, and I asked if anyone could tell where the grounds are..no one responded, so I'll put it out there again. How and where can I locate the grounds for the car. I'm assuming here that they're in the same location for all cars....

 

Hi,
I think there is nothing wrong with your car. My headlights dimm a little when I press brake too. It's not because something wrong but our cars have 4 lights to go from 12 watts to 27 watts by total of 60 watts [4X(27-12)=60]increase in an instant. I think it's normal.





I like when all four lights go bright when I brake so unless people behind me are blind, they should see my lights. I hate caravans or other cars with little taillights that use same bulb for braking and turning- it's f$%g crap because 1) not safe; 2) looks ugly

 

It's because of the slow reaction time of alternator to the change of current (power brakes), mine does it as well. Upgrading the wires related to the battery/alternator will help as well as removing corrosion.

 

my car does the same, and sometimes even drains the battery to dead.

try to roll your windows up (when they are already up) and does it do the same too? myne does aswell.

i think this may be something to do with the connection to the body/ie negitive with corrosion, tho its toooo cold for me to do anything about it. replaced the alternator a few times because i was having issues with it, but i belive this is annother whole differnt issue, the car has been dimming lights since i bought the car 2 or 3 years ago.

 

I would suggest u to get a ground wire kit, it helps in keepin the electrical bright.

 

my car used to do the same thing until I got one of those cheap ebay voltage stabilizers... You just hook the box up to the pos and neg cables going to the battery and it never does it anymore... I know I should probably go check my grounds but I just haven't gotten around to it and for $30 and less than 5 minutes of my time my headlights are brighter and no more dimming when I step on the brakes..

 

I have a ground wire kit and it does not fix the problem.

 

Just another vote for mine does that too! Can check grounds and connections as mentioned.

 

My car did the same. Headlights dimmed severely and stereo would kick off sometimes. I had a corrosion problem on + battery post that I finally solved with CRC battery cleaner and terminal protector. After replacing the battery and alternator to no avail I found corrosion in the two plug in connectors on the edge of the + terminal. After thoroughly cleaning the contacts with the CRC cleaner and some sandpaper strips the charging voltage at idle went from 13.2 to 14.5 and no more dimming lights or low battery.

 

Hmm, sounds like im the only person that not only do my lights dim, but my rpms drop dangerously low when i brake. Now i have to tap the brake rather than give a steady stop, otherwise i'd stall out.

 

yeah, i think i have something similar

 

give an example... link to one on ebay please.

give more information, mabe even pics! especially for... "corrosion in the two plug in connectors on the edge of the + terminal" - what does that mean in english? (no harm, just need to know!)

 

Corrosion would be green powdery stuff all over your battery connections. This can get very bad and can kill your electrical. Once it got so bad on my car that i stalled and was left dead in the road. Corrosion is no joke, it cost me 300 dollars for all new wiring.

As per the voltage stabilizer, i personally dont use one, but just type ina search in ebay an you'll find em. There a good investment if you run aftermarket stereos or extra power draining stuff like tv's.

 

The end of the positive terminal connector has the ring that attaches to the post and beside the ring are two connectons where the harness plugs in (at least that's the way my 97 is). I believe, and I may be wrong, that the entire electrical system, with the exception of the starter, is run off of those two wires. Like Maximaman my car finally got to where it would almost die when I hit the brake at low speed and I couldn't keep my battery fully charged. After cleaning those two connections it solved the problem on my car. It's worth checking out if your having the same problem.

 

thanks for the clairification! i will try and do that when i get some time. sounds like the issue, cause sometimes (not all the time) i can leave all the electrical components on, but once i turn on the lights the alternator cant keep up, this happens in slow stop and go traffic usually - but doesnt always happen, im thinking its this corrosion issue with the possitive connector/wires - negitive hasnt had any results - thats probably why those grounding kits dont help alot of people.

 

If it happens mostly at night then definately check for corrosion, and put on some corrosion disks, they help to keep the nasty stuff away.

 

i am pretty sure its your alternator....based on personal experience, i remember that was happening to me, and about 4 months later, my alternator just died on me on the freeway....
wasted my battery and 3 hrs of my life.....
even though the alternator is checked ok, i think sometimes they just die with no warning.....
hope this helps, i might be wrong though...

 

my interior lighting goes dim on idle, but it gets brighter as I press on the gas