famfedyk

On a 1997 ES300 with 110k on the odometer. Battery light on the dash came on so I put a voltmeter to the battery when the car was running. It read 11.85 Volts which led me to believe that the alternator was not charging. Replaced the alternator, but the battery light remains on and battery voltage is at 11.8 when the car is running. After I turn the car off, the battery voltage goes up to 12 V. Any ideas?

Arsenii

Hello,

Check all the fuses, see if any of them are bad. Then get a multimeter and measure the voltage between a B+ post and the body of the alternator, that will tell you if the alternator produces any voltage at all. If not, I am assuming your alternator is good, so check the wiring that comes to the voltage regulator.

If it is giving voltage, measure the continuity between B+ post and the positive battery terminal, do the same for the alternator body and negative terminal. That will tell you if the alternator connection is good.

P.S. Did you use a stock alternator for ES300? If so, I would suggest you to switch for a 100A (P/N: 27060-20140), or 130A (P/N: 27060-20190) alternator off of Highlander/RX300. ES300 are notorious for alternator problems, since 80A is not enough for this car.

Hope this helps and best of luck!

famfedyk

Where is the B+ terminal on the alternator and where is the voltage regulator located?

Arsenii

Here is the picture that shows voltage regulator connector, and B+ terminal.

To test the voltage regulator wiring, take a test light (just a light bulb with a couple of wires attached to it), connect one end to ground, and use the other end to check wires in the pigtail. The first wire in the pigtail (labeled L on the alternator above) is for the dash light to signal if there is no charge (which in your case works). The second wire (labeled IG on the alternator above) should have 12V only when the ignition is in the ON position. And the last one (labeled S on the alternator above) is a constant 12V supply.

Hope this helps and best of luck!

famfedyk

Thanks. And what fuse boxes should I be checking? Are they at various locations?

Arsenii

Yes, there are four fuse boxes in the car - three located in the engine compartment, and the last one is under the driver kick panel. Please refer to this diagram for more details.

Hope this helps and best of luck!

famfedyk

Is there some sort of secret in removing the 100A fuse? I'd like to pull it so as to check continuity but it just doesn't want to come out.

Arsenii

It is kind of an involved process to remove 100A ALT fuse - you will have to take apart the fuse box and unscrew it.

There is a window on top of the fuse, you should definitely see if it is still good. Besides, it is a main fuse, without it, half of the car would just die, so I would only check it if nothing else helps.

Hope this helps and best of luck!

famfedyk

Voltage from B+ terminal to battery negative terminal reads 14V. Voltage from B+ terminal to engine block or to battery ground cable reads 14V. Voltage at +/- terminals on the battery reads 11.8V. Does this point to a harness issue?

I do have continuity from alternator housing back to battery negative terminal.

Duralast (Autozone) battery that is one year old. The alternator is an O'Reilly's re-manufactured unit (Ultima R110998A)

Arsenii

Check the resistance between B+ and the positive battery terminals. If it is not close to zero, or there is no complete circuit, disconnect the battery, then unscrew 10mm nut on the B+ terminal and remove the wire under it. After that, sand down the crimp on that wire and check resistance between the wire and the positive terminal. If nothing will change, you may need to replace the wire going from the battery to the alternator, which is a quite involved process.

Hope this helps and best of luck!

famfedyk

B+ terminal to pos battery terminal indicates continuity but resistance is imeasureable on my multimeter (000.0.OHMS). I removed the wire and sanded the terminal and got the same result.

This is a new alternator that I just installed yesterday (under the belief that my old one was bad). I would think it highly unlikely that there would be something wrong with the new alternator, even though it is an O'Reilly's brand. Regardless, I plan on re-installing the old one since more than likely, this is not an alternator issue.

If the 100A fuse was blown, would it be fairly obvious?.

Arsenii

That wire connects to the battery through that fuse, so if it would have been blown, you wouldn't have gotten any continuity.

Start up the car and measure the voltage between B+ and positive battery terminals, then to the same for the body of an alternator and the negative battery terminal, you should see value close to zero in both of those scenarios. That will tell you if you have any voltage drops between the alternator and the battery. Continuity and resistance test don't put any load on the wire, so it is damaged only partially, it will not yield any results.

And just in case, you can sand both battery terminals down..

Hope this helps and best of luck!

famfedyk

For both of these scenarios, no resistance and no continuity.

Arsenii

You need to check DC voltage between B+ post and positive battery terminal. And the same for alternator body and the negative battery terminal. That will tell if you are loosing voltage on any of those connections.

famfedyk

I should stop and read these once in awhile! Haha...