last night i was driving and then all a sudden the headunit turns itself off and after a few seconds back on again. Then I notice that when i step on the brake the headlights dim. Whats going on with my car? Its a 95 SC300. thanks.

 

Battery, terminals on battery, or alternator.

I'm not sure on the I6, but when the alternator fails on the V8 it's usually because the power steering pump leaks all over the alternator. After you park your car, check the ground to see if you see any power steering fluid. Over the course of 2 weeks I had plenty on the ground.

 

I got kind of the same problem. When my headlights are on and if I try to roll my windows up whether they are down or not it doesnt matter, but if I try to roll them up the lights go dim along with the gauges and everything else like the radios LCD screen and AC screen. Its like the battery is draining and then if I let go of the window controls the power is back to normal. I dont know why it happens. I think the battery I have is REALLY small because the spot it goes in is really big and then the battery is like half the size of the spot and you can move it aorund in there. When I got the car the battery was already like that and I never changed it. I think I really need to tho. If someone has a pic of their battery in the car please post it. I'll try to post mine some time next week to see if theres a big difference which I'm almost 100% there is.

anyways thanks

 

My battery is only about 6 months old and its a gell cell battery, so I dont think its my battery.

 

hey what up Din... I had the same problem but more like the other guys car. when i would roll up the windows especially, but also when i pressed the brake the headlights would dim. I thought it was the battery cause when i got the car it came with a small *** die hard battery. I changed to a big **** Interstate battery and then my alternater died so i changed that too. Needless to say after all of that when i press on the brake the headlights still dim (a lil less than before though) and when i roll up the windows it does the same too. It seems that the bigger battery does help though..

Ryan

 

samn here.... have the same problem
power steering was replaced bout a year ago

 

i've went through this... and am going through this again (had my power steering pump replaced 6-8 months ago). whenever i tapped the brakes, car would ghost. whenever i rolled the windows, car would reset. flash my high beams? yup, car would reset. and i have a monster sized gell type battery.

how do i know my power steering is leaking? the huge puddle in my garage where i luckily threw down a garbage back (built up over a month).

buying a new battery will just delay the inveitable. the batter will simply die if the alternator is out because it won't recharge the battery while you are driving. in my case, sometimes it's fine and sometimes it isn't but it is getting progressively worse.

 

You know, when I was looking to buy a Lexus i asked several dealers etc., what goes wrong or what is a common problem with a Lexus and besides many saying nothing, I do remember one of them saying the power steering leaks and does leak on the altinator which eventually does cause the altinator to go out. I also remember after buying my sc300 and having the 60k service done, one of the things done or noticed by Lexus was a bad oring in my power steering.(I think this was the location of the O ring).

Maybe this is where your problem is located. The power steering causing a chain reaction like most people before me.

therriott15

 

I had the same problem awhile back (on and off for over a year). I've made several trips to the dealers but without any luck; they couldn't find the problem. So I decided to replaced the terminals on my batter with new ones... Since then, no more few-second outages when stepping on the brakes OR closing the sunroof and stepping on the brakes at the same time...

NOTE: These few second outages happen quite often during the raining seasons or over casted days...

 

I don't think it would be a problem with the battery because the battery is used only to start the engine and it is used when your engine is shut off and you're using your accessories (radio, lights, etc). When your motor is running, the alternator is generating all the power for accessories and the battery is storing energy. So it should be a problem with the alternator, or the connections, like mor-power said.

 

Check your ground connections because the original ground isnt really "that" good and over time you get dirt buildup etc. If need be, make some extra ground connections to the battery and chassis/Engine.

Toan.

 

Thanks guys I will check all these out tomorrow. Is there anyway I can test the alternator without removing it from the car? IF it is the alternator should I have it rebuilt or jsut replace it with say one from Autozone or something. Also is it hard to replace the alt by myself?

 

hey din to check the alternator you gotta have a votmeter. the small ones from radio shack are fine. just touch the red aligator clip to the positive terminal on the alternator and the black wire to a good ground and start ur car. you will then get the reaDING of the alternator.

Ryan

 

I have checked both my SC300 and SC400 and if I start the car and disconnect the battery I see the behavior you guys indicate. If driving the car can cut out. The alternator is not sufficient all the time. It will run but it may stall too.

 

I have heard to check the alt i should start the car then disconnect the battery terminals and put the meter to the cables and if it doesnt read 12v its bad. Is this true?