Question about 1998 Lexus ES 300

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99 es300 will not charge battery if rpms are under 1200 and has new battery and have tried 3 different brands of alternators.All wiring is good and am getting power to all wires at alternator.Still have the same problem.

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  • jr4453 Jun 21, 2009

    I bought this car with this problem,it has not had anything added to the system.The grounds are the only thing i have not check yet but i have not seen anything off hand loose.As far as pulley size it has the one that came on the car so that should not be the problem.In most cases if the igniter wire is hot to the alternator it should charge at idle as well as higher speeds.You can turn off all accessories and it does the same thing.There are three wires on the plug can anybody tell me what kind of power or grounds are supposed to be there when running are not.I have a wiring diaghram but it does not lell what is on each wire at all times running are not.

  • jr4453 Jun 21, 2009

    Every connection is clean and tight.With a volt meter on the battery the volts go from 14.2 at 1300 rpms and up and at 1200 rpms and down the volts start dropping until the battery will not run the car anymore.

  • Joel Friedenberg May 11, 2010

    OK - the alternator works and the battery charges above 1200rpm. I believe the stock alternator for the 99 ES 300 puts out about 80 amps max, so at idle there's going to be a pretty significant voltage drop - BUT it sounds like an RPM problem; above engine RPM of 1200, everything's OK.

    I'd check for belt slippage, wrong length belt or malfunction of belt tensioner. Good Luck!

  • Joel Friedenberg May 11, 2010

    Thundergod is correct; a smaller alternator pulley would produce higher RPM's and higher voltage output at idle, but I would not think you have to go that route for a stock alternator with stock elec. equipment.

    This may seem like a simplistic question, but how do know the alternator is not charging at idle? What are the symptoms? Does your instrument cluster have a voltage gauge. If so, what does it read at idle?

    I take it that the BATTERY TERMINALS are really clean - no corrosion, and the ground wire to engine connection has been checked for corrosion.

    Again, check for belt slippage and/or belt tensioner function.

  • Joel Friedenberg May 11, 2010

    Have you added any high power audio equipment or driving lights prior to the no-charge problem?

    Are you having the no- charge problem regardless of whether lights, accessories, blower, etc.., are on or off?

    Have you checked the GROUND(s) connection(s)?

    Have you replaced the drive belt or checked to see if the belt is slipping?

  • Richard Scordino May 11, 2010

    See if you can find a smaller front alternator pulley it will turn the alt faster. problem may not be electrical.

  • Rodolfo Campusano
    Rodolfo Campusano Jun 09, 2016

    Did you find the fix I'm having the same problem

  • Rodolfo Campusano
    Rodolfo Campusano Jun 09, 2016

    Did you find the fix I'm having the same problem



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I believe the voltage regulator is controlled by the ECM ....computor

Posted on Jun 09, 2016


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SOURCE: alternator in a 99 olds' intrigue

just do it

Posted on Sep 30, 2008

  • 74 Answers

SOURCE: Car won't stay running.

alternator does not hold a charge it simply charges the battery by unhooking the battery you are taking all voltage from computer and car will not run the proper way to test your alternator is use a multimeter and check voltage at battery while car is running if you have 13-14 volts it should be fine.

Posted on Nov 18, 2008

  • 55 Answers

SOURCE: No dash lights, power seats or windows. alternator not charging. Engine runs

  1. It might be that when you changer the battery post you might not have connected all of the leads on the positive post. You might also check for blown circit breakers caused while changing the terminals.Try using a dc tester and search the main breakers for power. If you have the manual it shows the breakers and links in the bulb replacement section. JOHN-LA.

Posted on Sep 01, 2008

  • 185 Answers

SOURCE: 99 Olds Intruige removing the alternator

disconnect the + lead of the battery
Remove the wires going to the alternator. Mark them with a piece of tape so you can put them back to the same terminal.
there are probably two bolts that need to be removed. One will be fastened to a slotted strap. Removing this one will allow the alternator to pivot on the remaining bolt. This will be the one that allows the fan belt to be removed from the pulley on the alternator. Removing the 2nd will allow the alternator to be removed from the engine.
Installation of the replacement is the reverse procedure. Aftere you install the 2nd bolt, put the fan belt back in the slot and pull the alternator so the slack is taken up in the belt, then tighten the bolt

Posted on Oct 22, 2008

  • 81400 Answers

SOURCE: ECM Replacement

This is a useful link on the code difinition, what it looks like is that the new ECM has a specific key code from the original car, there is a procedure for this issue, either you get new keys made from Lexus/Toyota or find out how to erase the code in the ECM, this code is why the eng won't start, I have no Lexus manuals at home nor does, at this point I would try to get the info from, but it is a pay site, unlike this site which is free, and by the way I'm not employed by, just trying to help on my own time, I am a retired techincian.

Posted on Dec 01, 2008

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