Apparent Alternator Failure.

[wwest]

My '92 Lexus' intrument panel lit up like a pinball machine which caused me great concern.

But on researching via the shop manual it appears that Lexus wasn't satisfied just illuminating the battery "no charge" light with no alternator output, they have "OR" diodes to at least 4 other system failure lights.

In any case its parked in a friends driveway and I would like to drive it home, ~5-7 miles, to repair it but it cannot find an easy or simple way to keep the (now recharged) battery from being discharged into the alternator rotor "field".

Anyone have suggestions..??

[Jerry Bransford]

My '92 Lexus' intrument panel lit up like a pinball machine which caused me great concern.

But on researching via the shop manual it appears that Lexus wasn't satisfied just illuminating the battery "no charge" light with no alternator output, they have "OR" diodes to at least 4 other system failure lights.

In any case its parked in a friends driveway and I would like to drive it home, ~5-7 miles, to repair it but it cannot find an easy or simple way to keep the (now recharged) battery from being discharged into the alternator rotor "field".

Anyone have suggestions..??

Disconnect the alternator's charge lead from the battery? I haven't looked at my LS430's alternator (I don't even think I can see it) but it's easily disconnected on my Jeep.

[wwest]

My '92 Lexus' intrument panel lit up like a pinball machine which caused me great concern.

But on researching via the shop manual it appears that Lexus wasn't satisfied just illuminating the battery "no charge" light with no alternator output, they have "OR" diodes to at least 4 other system failure lights.

In any case its parked in a friends driveway and I would like to drive it home, ~5-7 miles, to repair it but it cannot find an easy or simple way to keep the (now recharged) battery from being discharged into the alternator rotor "field".

Anyone have suggestions..??

Disconnect the alternator's charge lead from the battery? I haven't looked at my LS430's alternator (I don't even think I can see it) but it's easily disconnected on my Jeep.

I wish...

There is a separate 40A fusible link from the battery to the alternator "field" but it branches and splits serveral times to "feed" other components on the way to the alternator. Thinking seriously about crawling under and cutting this wire as it goes into the alternator and then re-splicing it after repairing or replacing the alternator with a rebuilt one, $200.

[ko90ls]

you could prob just replace the alternator at your friend's house. if you replace it then all you need to do is take off the 2 14mm bolts and the 10mm bolt that holds the tranny lines in position (on bottom alt bolt next to oil pan.) very simple, can be done with removing just the upper intake parts until the MAF and loosening the drive belt. then hit the 14mm and 10mm bolts and disconnect the plug in the back and the 12mm bolt. can easily be done with your lexus jack or car ramps. there is just enough room to drop the alt down and remove/install from under the car, just wiggle it a little.

[wwest]

you could prob just replace the alternator at your friend's house. if you replace it then all you need to do is take off the 2 14mm bolts and the 10mm bolt that holds the tranny lines in position (on bottom alt bolt next to oil pan.) very simple, can be done with removing just the upper intake parts until the MAF and loosening the drive belt. then hit the 14mm and 10mm bolts and disconnect the plug in the back and the 12mm bolt. can easily be done with your lexus jack or car ramps. there is just enough room to drop the alt down and remove/install from under the car, just wiggle it a little.

I got a tad braver than maybe I should be, fully charged the battery, drove it 11 miles to home, battery down to 10.11 volts but engine ran fine until shutdown.

Now to see just what's failed......

[wwest]

And the answer is....

Slip ring brush...

Positive side slip ring brush is worn down and tilted sideways.

Anyone know why positive side would wear first?

And being the Cheapskate that I am.....

Can one still buy slip ring brushes (only) for a 92 LS400 alternator?

[Beowulf]

Can one still buy slip ring brushes (only) for a 92 LS400 alternator?

Yes, and you can get them from a Toyota dealer. I can dig out the p/n if you need it but I know they use the same brushes as a 1997 Toyota Land Cruiser.

-B-

[wwest]

Can one still buy slip ring brushes (only) for a 92 LS400 alternator?

Yes, and you can get them from a Toyota dealer. I can dig out the p/n if you need it but I know they use the same brushes as a 1997 Toyota Land Cruiser.

-B-

Lexus had them in stock, <$30.

[Beowulf]

Lexus had them in stock, <$30.

Toyota dealer had the alternator brushes in stock too. p/n 27370-75060 $12.67.

They stock the serpentine belt too. p/n 90916-02586 $35.60

I also picked up a thermostat and gasket, PCV grommet and I should have picked up a few other bits like oil pan gaskets and the good 90915-20004 Toyota oil filters.

-B-

[wwest]

Lost weekend,...FRUSTRATING weekend...!!

Problem turned out to be not only worn out slip ring brushes but also internal regulator, installed rebuilt alternator.

[John2]

beowulf? is that the same that is in the MUD forum? you and i have the same cars/trucks?? interesting....

i have 92 ls400

97 LC

you?

john

[lenore]

Lost weekend,...FRUSTRATING weekend...!!

Problem turned out to be not only worn out slip ring brushes but also internal regulator, installed rebuilt alternator.

When the slip ring went crooked it probably fried the regulator, by the Way they sell that also...

[Beowulf]

beowulf? is that the same that is in the MUD forum?

Yes, the same. Replied to your PM too.

-B-

[dluebbe]

Any guesses as to what could cause me too go through 4 alternators in one year on my 92 ls400? It had a power steering leak with the first one then I fixed the power steering pump and replaceed the alternator then I have just recently went through three more. Any answers or opinionswould be greatly appreciated I really wanna fix this problem

[curiousB]

Any idea what the failure mode is of the alternator? The fluid leak is a common problem that ruins the brushes contacting the rotor (field) rings. Sounds like you fixed that problem though.

Anything blocking airflow to and around the alternator. That could cause it to overheat and fail.

Just poorly remanufactured replacement alternators? Where do you get the replacements? I just spent several hour changing an alternator on my daughters Ford Escape. Massive job due to its location. The new alternator failed a couple days later. errrrrrrrrrrr!!! Had to do it a second time. Lousy reman part from O'Reilly's. They were really good about swapping it under warranty though. Still several hours wasted. Second has held up a couple months now.

[dluebbe]

Ihad bought all of them from O'Reillys everything seems to be open no blockage around alternator. Could it be shorting out somewhere, or my positive battery terminal being corroded.

[curiousB]

No as stated in the other thread you started, corrosion wouldn't kill an alternator. Might explain a dead battery from time to time.

Does this car have any modifications to the electrical system. An exotic sound system, DC/AC inverter for some AC powered load, a winch? .... or is the electrical system stock? Just wondering if some strange external load that is creating havoc.

Not sure of a loose charge wire from the alternator to the battery could be a problem. Is the lug/stud connection on the alternator clean and free of corrosion? What about the wires integrity all the way to the battery? I wonder if there is some weird load dumping scenario occurring when alternator is kicking out max power and then the wire wiggles open circuit. The energy in the core has to go somewhere and maybe results in a high voltage that could fry the internal electronics of the alternator. Seems unlikely but my only other theory is poor quality remans from O'Reillys. It is odd both you and I have had quality issues on alternators from them. I suspect their QA procedure is too superficial and fails to properly stress test the alternator under load.