Battery light remains on after replacing several things.

Tiny
OHISABELLA
  • MEMBER
  • 2001 FORD MUSTANG
  • 4.6L
  • V8
  • AUTOMATIC
  • 109,000 MILES
The problem started when the car died out on the way home from work. I jumped the car and then took it home. It made a clicking noise when I tried to roll the key over in the ignition and the battery light showed. The car made it home but would not turn on.

I was told that it could be the alternator.
I then proceeded to troubleshoot the problem. I replaced the alternator myself and had it checked by a mechanic to see if it was a bad alternator. Everything checked out. I replaced the terminals because they had slight corrosion. I also bought a brand new battery as well from Auto Zone.
Now, the car will turn on every time I try to start it. However, the battery light is still on and if you go to drive the car it ends up dying out before you reach your destination.

What could this possibly be causing the light to be on and the car to die out?
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Thursday, June 19th, 2014 AT 7:09 PM

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Tiny
CARADIODOC
  • EXPERT
"The car made it home but would not turn on"? How is that possible?

Sounds like the generator still isn't working. For future reference, if at all possible, avoid having a generator tested off the engine. Many in-store testers don't do a good job although they can tell whether it's working or not, but there's a lot more to it than that. Given the fact the battery runs down while you're driving, we can assume the charging system isn't working. If you want to verify that, use an inexpensive digital voltmeter to measure the battery voltage. Once it's fully-charged it will measure 12.6 volts. If it's discharged, it will read closer to 12.2 volts. With the engine running, it must read between 13.75 to 14.75 volts. I suspect you're going to find it stays well below 13.75 volts.

There's a number of things that could have been caused by the old generator. First, there should be a yellow wire in the connector. Back-probe through the rubber seal to read it's voltage. You should find full battery voltage there all the time. If you find 0 volts, look for a blown blue 15 amp fuse. If that is okay, measure the voltage on the large bolted-on output wire. With the engine not running, you must find full battery voltage there too. If that is missing, look for a blown very large fuse in the under-hood fuse box. If one is used for that application, it is usually bolted in.
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Thursday, June 19th, 2014 AT 9:11 PM

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