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Possible Bad Alternator


gremio
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My 91 LS was parked on a sunny day and it was very hot when I got inside. Same time I was starting the car I was pressing all my four fingers on the four window switches. Right after the engine started, the battery, brakes, coolant, and add engine oil lights showed up on the dash board.

DID I FRY THE ALTERNATOR!!

While the engine is running, I unplugged the + wire connected to the battery and the engine died right away. This means the alternator is not producing juice, RIGHT?! Could it be a fuse that got blown out?!

My P/S pump is kind of oily wet and I have never experienced any leakage problem. Fluid level never went low in the past BUT my steering is kind of HARD. On a cold morning, steering seems to be soft and get harder after the engine temperature gets higher. Would replacing the P/S pump fix my hard steering problem?!

If I am having a bad alternator, do you guys recommend replacing the P/S pump at the same labor time?!

AUTOZONE should have those two parts as a rebuilt, are they any good?

Your comments are greatly appreciated.

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When you unplug the battery with the engine running the output of the alternator will go to infinity and BEYOND!

No, seriously, the ability of the battery is act as a current sink, load, on the alternator is an integral part of the charging system. When you open the battery the result will oftentimes be huge high voltage spiking of the alternator output often resulting in blowing up multiple elctronic components. I'm not really surprised your engine quit the instant you opened the battery circuit. But I am surprised everything worked afterward.

The first thing to do each time you have suspicions of electrical problems of this type is remove the battery terminals, engine OFF!

And the clean and burnish the battery posts and the connectors and then reinstall. This procedure is a good one to follow each and every spring regardless.

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Same thing happened to my '91 LS a few months ago when I started it up except I wasn't playing with the power window switches. Found out a leaking power steering pump had slowly dripped fluid into the alternator over a period of weeks/months. Quick fix solution is to install a new alternator with a home made cover to protect it http://www.saber.net/~monarch/alternatorcov.jpg. Long term solution is to rebuild or replace the power steering pump and it flow control valve. Also the power steering solenoid filter needs to be cleaned. Its located on the steering rack. The power steering system is a routine trouble point on the '90-'94 LS400's after 12-15 years of service.

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Here are more updates (after I cleared the trouble codes by removing the EFI fuse):

When I turned the ignition switch On (without starting the engine), I have noticed the "BREAK" light in the dashboard is "On" knowing that the foot emergency break is fully released!!!!

After starting and driving the car, I have noticed the Air Suspension Pumps are NOT pumping. The height indicator on the dashboard is showing "high" even when I pressed on the height button to the NORMAL height!!!!

Again, My "Battery", "Add coolant", "Add engine oil", and "Break" lights are still On after starting the car. If I'm having a bad alternator, the electrical system wouldn't know that till you start the engine, RIGHT?!! If the is the case, Why the previous mentioned lights were On even before I started the car?!!!! (except the battery light which it should but not others).

Should I drop the car off at Lexus dealer to diagnose the problem? Please advice.

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Those are all symptoms of a bad alternator. You might want to have the car towed because your battery could end up getting discharged after as little as 5 miles of driving and then you'd be stranded (unless you carried a spare battery with you)

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Those are all symptoms of a bad alternator. You might want to have the car towed because your battery could end up getting discharged after as little as 5 miles of driving and then you'd be stranded (unless you carried a spare battery with you)

With engine running and battery connected check the voltage at the battery terminals it should be around 13.8 volts if it is only around 12.8 your alternator is bad if 13.8 or higher alternator is probably ok.

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Just got my car fixed at a local mechanic shop. Alternator was dead.

Quick notes to all:

- For Lexus's with Air Suspension type of Struts, the air pumps will NOT operate if your alternator goes bad. Pumping air will be automatically disabled to prevent the battery from a quick discharge! Or, the battery charge is not strong enough to run the pumps!

- Next time you start the engine, turn off radio/CD/cassette, all lights, and do NOT power the windows...

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for the future reference NEVER and i repeat NEVER disconnect battery terminals while engine is working or you risking paying for new ECU and couple of ECMs. i dont think you have dead alternator, at least yet, signs of dead alternators are dimmed lights, non working radio and battery indicator will be constantly on.

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