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Jared D
Jared D, ASE Certified Technician
Category: Lincoln
Satisfied Customers: 1860
Experience:  Shop Supervisor at County Fleet
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2004 lincoln aviator replaced alt. and is charging but dash

Customer Question

2004 lincoln aviator replaced alt. and is charging but dash says check charging system and battery light is lite up as well.. need to diagnose issue
Submitted: 1 year ago.
Category: Lincoln
Customer: replied 1 year ago.
is more info needed?
Expert:  Jared D replied 1 year ago.

The best way to diagnose this one would require a scan tool:

Check the PCM for service codes. If code P1246 is setting from this PCM in KAM, replace the replacement alternator assembly as your new alternator is likely bad.

The PCM sends a signal to the voltage regulator on the LG/RD wire to excite the alternator into charging output operation. Once this signal is received by the alternator, the voltage regulator should control the output of the alternator based on the system voltage it is detecting on the Orange/Light Blue (OG/LB) wire. The alternator output feed is the Black/Orange (BK/OG) wire at the B(+) terminal of the alternator.

Check for that code and let me know what you find.


Thank you for the opportunity. I love helping people fix their cars and saving them money. Please keep in mind that most problems will require some diagnosis to get them sorted out. I will be here to help until you are satisfied.

If you do not plan to rate my response once you are satisfied please let me know as soon as possible. As an expert on Just Answer I only get paid for my service here based on positive ratings from you, the customer. If you do not plan to rate, and therefore compensate me for my time, I need to focus my efforts on customers who do.

Customer: replied 1 year ago.
p1246 is the code before replacement car died on highway and towed in
Expert:  Jared D replied 1 year ago.

We've had a lot of bad luck with alternators on these models if we use either after-market brand or re-manufactured alternators. They will work, but for some reason not well enough to turn off the charging light. They have gotten better over the years, but for some reason the 2004-2005 ford 4.6L doesn't like anything other than a Ford Motorcraft alternator. The worst part is that the Motorcraft alternator is easily twice the cost.

What type of alternator did you put on?

Customer: replied 1 year ago.
advance/car quest #7773an new...
Expert:  Jared D replied 1 year ago.

I have a fleet of 1200 Fords that I have to keep going every day. I'm willing to bet that you have a bad new alternator. Advance uses World Wide (or at least they normally do) to make their alternators. They occasionally have out of the box failures on all models, not just the overly sensitive 2004 Ford/Lincoln 4.6L.

Customer: replied 1 year ago.
dropped of another,will change it and let you know... not the most fun one to change
Customer: replied 1 year ago.
any other way to determine it is the alt by voltage specs or other?
Expert:  Jared D replied 1 year ago.

Not really. We have yet to be able to determine why one alternator will turn the light off but another won't while both seem to be outputting sufficient voltage.

Customer: replied 1 year ago.
2nd replacement seems to bobble voltage ALOT more then previous.. a good .75 volts.. light,message,is off now thanks Ed
Expert:  Jared D replied 1 year ago.

So it looks worse but the computer thinks it's better? How strange.

Let me know if you need help in the future. Please don't forget to rate.

Expert:  Jared D replied 1 year ago.

Please don't forget to rate. We don't get paid if we don't get a positive rating.

Expert:  Jared D replied 1 year ago.

I seems that we got this one sorted out, please don't forget to rate me and therefore compensate me for my service.