pmarr

99 LS400 220+ miles. Daughter's car. Replaced battery about three months ago and now the battery light is on. How long will a fairly new battery last with no alternator support? A week? 3 days? Anyone have experience? Will get it voltage tested tomorrow to confirm. Currently fluid everywhere as expected. Belt nice and tight.
Thanks in advance!

djamps

Could be minutes, hours, or days... no way to know. I suggest replacing the alternator ASAP and making sure the power steering pump isn't leaking, as the new alt will be destroyed quickly if so.

Banshee365

It will last 2-4 hours if the alt isn't charging at highway speed. Change it now.

pmarr

2-4 hours! Wow, not good. PS pump will be replaced as well as it is leaking. Thanks for the input

YODAONE

The future is uncertain and the end is always near.

If replacing, go for higher efficiency 130A output alternator from 2001-2003 LS430...Same alternator connector...

It has a third mounting flange hole....buy that bolt and nut from Lexus.

check out my alternator posting on the subject

RA40

iTrader: (6)

In addition if the battery is deep discharged it may be damaged and as a result have a much shorter lifespan. Change it ASAP, don't drive it.

oldskewel

iTrader: (1)

When the alternator went out in my '91, I only had half an hour of city driving before it died. So yes, plan for the worst.

Also, when it died, it did it right as I was driving. I shifted to neutral and conveniently coasted to a stop, parking at the curb. My lights, radio, everything optional was off.

When your battery is bad, once jump started you can run almost indefinitely on your alternator. When your alternator is bad, the battery will just drain out and you're done.

dicer

And if the head lights are on time is very short.

bradland

YODA I'm intrigued by this option. Could you elaborate a little...? Maybe post a link to your post.

lextout

check your valve cover gasket and crank/cam seals while your in there as they may be a possible culprit

YODAONE

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/807894-1998-2000-ls400-alternator-upgrade.html

some images of both alternators...I believe the increase from 100A to 130A was attributable to profile of windind wire 100A Alternator with 2 mounting ears
130A Alternator...(2001-2003 LS430 only has same harness alternator plug connector as LS400 )has 3rd mounting ear...but will bolt in with special bolt from LS430
Positive cable stud on LS400 Alternator..notice round wire.. LS430 postive cable mounting stud...
Notice the windings wire profile inside casing...appears to be more square (higher efficiency design) or perhaps reconfigured windings.


Image showing 1UZFE engine with stock alternator installed.
Image depicting 3UZ-FE engine (LS430) with 3rd mounting ear...simply acquire the bolt and from Lexus and installation is bolt in.
Power curve (Denso) for 130A alternator. (I believe this is power curve for same Denso alternator in 2001-2003 LS430) .the take away is better power production at lower RPMs where our engines tend to reside.over 1997 and earlier LS400's which have 2,700 RPM stall speed vs. 1998-2000 LS400 @2,200 torque converters and taller gearing ~3.73 vs ~3.26 for 1998-2000 LS400.
It is my belief the battery will not have to work as hard at lower RPM's and thus will last longer.

YODAONE

DO NOT use aftermarket rebuilt P.S. pump...sure they provide lifetimec warranty, but what good is that if you have to keep replacing it along with your alternator...

Buy new P.S. pump from Lexus dealer.

Ditto for the Alternator, buy only Denso certified rebuilt...not aftermarket stuff...this you can obtain from dealer or Rock Auto...go 130A.

pmarr

I made it to the shop and dropped off car. White knuckles as I waited forever at stop lights waiting for the car to die, thankfully she made it in smooth LS fashion. I have requested the mechanics use only OE parts, would this be the same thing? I do not want aftermarket anything..... Requested a diagnostic prior to work just to be double sure. Headlight leveling warning came on while driving, hopefully related to current issue and not another one. 130 amp. Got it. Thanks all!

YODAONE

The shop should receive wholesale parts pricing from dealer...make sure you benefit.

Also...ask to see old parts. The alternator may have core charge from dealer.

A new power steering pump does not have core charge with the dealer, so the shop should return it to you.

bradland

Ok I've read your post from a little over a year ago and studied all the pics. So far all I see is you asking other forum members IF this mod has been completed successfully. In a little over a years time no one, including yourself, has responded to the thread to say it has been completed successfully. I see a pic of a 1UZFE motor with a stock alternator and a pic of a 3UZFE motor with a stock alternator. Please excuse me if I seem pessimistic but I'd still like to see some evidence of this as a possibility. " simply acquire the bolt and from Lexus and installation is bolt in." isn't quite enough for me...