Streamline

Ok. I just got home.
I haven't looked at my car yet, but this is what is occurring.

When the car is idling or coming to a stop (near complete stop), the battery light comes on.
When I step on the gas (producing load), the battery light goes away.
Just as a note, the lights do dim a bit when I introduce a bit more load on the electrical system (such as putting on my turn signal).

The car starts just fine.

So I'm assuming it is isolated to just the battery itself?

I'm going to check the cables/terminals for corrosion.
But in the mean time, thought I would ask to see if you guys could help isolate the problem.

I'd rather it be the battery, than the alternator.

Am I correct on my diagnosis based on what I'm experiencing?

TMaxxTim

Could be the alternator as when you are at an idle its not spinning as fast therefor creating the low voltage because the alternator is going bad, however when you step on the gas or are moving the rpm's are up and the laternator is still producing enough power to move. Could also be a bad battery for the same reason, probably going to need to have both checked out. Just go to autozone, if the battery checks out then you know the culprit.

Streamline

Ok. So I checked the terminals last night, and they are clean. No corrosion whatsoever.

So, that leaves either the battery itself (not a bad connection) or the alternator.

I popped off the battery vents, and checked the water levels. They seemed fine, but I added just a bit of distilled. Then I charged the battery overnight.

This morning, battery light still comes on. Same symptoms where the light will come on when at idle. Once RPMs go above 2,000...the light goes away. Windshield wipers are EXTREMELY slow.

I thought I noticed the battery light come on when I was going on an incline on a freeway. Didn't get a chance to repeat this "test" to see if it will occur again. Not sure if this has to do w/ the water level in the battery.

Hmmm.....will post again later once I get the battery tested.

audi2nr

iTrader: (1)

check the tension on your serpentine belt, if its too loose it might be slipping on the alternator pully causing your battery to not charge.

mitsuguy

iTrader: (2)

alternator... everytime... chances are your power steering pump is going as well, as 90% of the time, the alternator fails because the power steering pump has leaked fluid onto/into it...

hemogoblin

Sorry... same thing happened to me about 7 months ago. Alternator.

np20412

the SC300 doesn't have that problem like the SC4, but its probably a failing alternator nonetheless

twizted

iTrader: (2)

Def alternator....

mitsuguy

iTrader: (2)

bah, for some reason I get it in my head everyone here has a 400..

jpw

Hi Mitsu,

I have the exact problem you're talking about. Have you ever done this yourself ?, ie the PS pump. My dealer in bellevue, Washington, wants about $1200 to replace the ps pump and just re-do the brushes on the alternator.

I've replaced alternators before but not a PS pump - looks like they're about $300 or so at napa...

tanks

mitsuguy

iTrader: (2)

we charge $74 / hour labor, so I will quote based on that

1.6 hours R&R power steering pump ($118)
pump assembly - list $488 (dealer)

.9 hours R& R alternator ($66)
alternator - list $338

total: $1012 + tax and miscellaneous parts (I'd usually do belt and power steering system flush with this); so, the $1200 from the dealer isn't too far off... however...

now, where you can save some money is the parts....
find a hookup, and a Bosch replacement alternator costs $132.00 and a power steering pump runs $142.00 these are OE designs (if not the actual OE part)
even paying a shop labor, this would save you $500 easy.... I come up with $458 total, then the miscellaneous BS...

$loJam

What are you talking about.....I had the same prob 2 years ago on my 300....the ps pump drips on the alt...had to replace both...I went aftermaket on the alt (bosch) and on the steering pump and had lexus do the pump and some ****head do the alt which he screwed up my alarm system. Save d a bunch with aftermraket parts...screw buying parts from the Lex stealership if you can.

jpw

thanks guys - I've decided to take it to my regular mechanic, who I've found throughout the years to be honest and fair. I haven't taken my lexus' (I have a 92sc400 and a 93gs300) to him , though..

preciate the feedback ! Next I have to get on those failing rear hatch pistons....

mikeloc24

This is very incorrect. On the 300, the power steering reservoir (which is what drips on the 300's) is located on the driver's side of the engine towards the front bumper. The alternator is on the passenger side of the engine near the exhaust manifold. It's impossible for that reservoir to drip on the alternator.

Now what DOES drip onto the alternator in the 300's is that damn o-ring in the distributor cap.

jpw, buy an aftermarket alternator and have your mechanic swap it out. I just did the same repair on my SC 3 weeks ago after experiencing similiar symptoms and it fixed the problem. Good luck.

mitsuguy

iTrader: (2)

I don't have a SC300 to go look at, but it seems what you are saying is that the power steering pump is not located on top (or above) the alternator???

And that the Pump in 300's don't leak and it is actually leaking from the reservoir instead???