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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
Satisfied Customers: 4944
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Toyota corolla: The alternator was squeaking on 2005 Toyota

Customer Question

The alternator was squeaking on 2005 Toyota corolla. I replaced the alternator and the battery. Now there is a very dim battery light on. The alternator is pushing out 14.6. Why is the battery light on?
Submitted: 2 years ago.
Category: Toyota
Expert:  Toyota Service replied 2 years ago.
Hello. Welcome to Just Answer. Please allow me to assist you.
The battery light is on weak because the voltage regulator that is built into the alternator has a defective diode. The diode is in place to prevent the battery light from coming on when the alternator is putting out the proper voltage. Only when the voltage drops below 9 volts should the light come on.
In this case, you have a defective alternator (common with inexpensive rebuilt units, where the rebuilders do not replace the voltage regulator assembly).
The recommendation here would be to return your alternator, state it is internally defective, and get a replacement
If you have any questions, please feel free to reply
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Customer: replied 2 years ago.
I replaced the alternator, they tested it the diognotsic machine. Checked out okay. Installed it and still have a low battery light
Expert:  Toyota Service replied 2 years ago.
The diagnostic 'machine' does NOT check the diodes inside the voltage regulator.
The machine only checks output voltage and output amperage.
Nothing else.
To check the diodes, the alternator needs to be disassembled and the diodes checked individually with a diode tester.
Customer: replied 2 years ago.
This is the second one that I got. They took it out of the box and checked it out for that. It stated thT it passes the electrical check. What else could it be
Expert:  Toyota Service replied 2 years ago.
There is the rare possibility that the pulley on the alternator is not allowing the alternator to turn fast enough.
It is also possible that you have some kind of small crossfeed inside the body computer/integration relay. This too is rare, but possible.