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Old 11-01-2010
Thread Starter
Join Date: Nov 2010
Location: Ottawa, Canada
Posts: 3
2003 Ranger Alternator Mystery

Hi Guys,
my first question on this forum. I am about to go crazy here :)
It's been a week that i am trying to fix my 2003 Ranger.
It has 4.0 sohc engine.

a week ago , I started my ranger and battery charge light came on.
The weird thing was that it was comming on with different intensity as if the wire was lose.

Well, i tought it's time to check battery and alternator.
Took it to the local parts store and battery checked-out fine.
They could not test my alternator since they did not have an adapter for ford.
So i took it to another store and this time they did not have ford alternator electrical connector. Five stores later i finally gave up and order another used alt from e-bay.
Alt came in and i installed it and same thing happened.
Charging lite is on and it does not charge the battery. I have avbout 12.20 volts on the battery when checked with volt metar.

Did lot's of troubleshooting with help from another site and could not fix it.
So i said, maybe i got non-functional used alt. Let's get the new alt. After buying new and installing it I got the same issue.
So this is where I am right now:

black/orange (b+) terminal is producing same voltage as on the positive battery terminal.
the voltage depends of charged state of my battery. When it's fully charged it reads 12.65 v. When i let the track idle for 5-10 minutes drops below 12.

I disconnected black/orange (b+) wire
and connected volt meter directly to the alt output.
While idling it produces, about 15-20 volts

If i increase RPM`s it gives me up to 45 volts.
When i connect black/orange wire back it gives me same
output that I have on the battery (12 volts)

yellow/white wire gives me about 2 volts less the the battery so about 10 Volts while truck is running.
When it`s not running it gives me same reading as on B+ Terminal (12 volts)

Black/white and another white (s terminal) wires are connected and it does not appear that any fusable links are bad.
I have checked all fuses and they all look good.

I am at this point willing to take any ideas to try to resolve this issue?

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Old 11-01-2010
Join Date: Mar 2007
Location: Upstate,NY
Posts: 2,598
Clean the negative (ground) connections from the battery to the frame and body and engine.
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Old 11-01-2010
Thread Starter
Join Date: Nov 2010
Location: Ottawa, Canada
Posts: 3
Originally Posted by OTRtech View Post
Clean the negative (ground) connections from the battery to the frame and body and engine.
Wow, I just cleaned small wire connector going from negative battery terminal to the frame and now started partially charging.
The red light goes on and off and i could see lights getting bright and then dim again so i will continue and clean other connections to the frame and engine.
Would you know where main frame connection is located?

Thank you very much. I am almost there :)
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