"Check Charging System" error with new alternator??

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scjmc

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I have replaced my intermittant failing alternator with a new NAPA unit. I had problems where it would not charge for a while after I started the car. I could verify this with a voltmeter. Whenever the "check charging system" message apeared I was running off the battery 12.4- + volts. I now have a new alternator and while it is charging (14.5 volts verified with a multimeter) I am still getting the error message and lit battery icon on the dash. Any thoughts?? Fuses related to the charging system look good. To reiterate the alternator is charging properly, but I am still getting the error message likt it is not. Tried disconnecting battery too...
 
I hope you didn't disconnect the battery with the engine running...
The alternator light is a realtime indicator. There is nothing to clear.

The A circuit 30-BA25 (RD) carries 13-15 volts. The generator regulator compares the A circuit voltage to an internal set point voltage to determine when to operate. This duty cycle is output to the powertrain control module (PCM) on the GEN MON terminal 8-BA25 (WH/RD). In the case of failure, the GEN MON terminal is 0% (0 volts), or 100% duty cycle (12-14 volts). The I circuit 10-BA25 (GY/RD) carries 1-8 volts with the engine running and is only used to turn the generator on initially. The B+ output circuit 30-BA6 (RD) is the generator output supplied to the battery and the electrical system.

* Possible Causes generator
* instrument cluster
* powertrain control module (PCM)
* I circuit 10-BA25 (GY/RD) open or short to ground
* GEN MON 8-BA25 (WH/RD) open or short to ground
* A circuit 30-BA25 (RD) open
 
I had that same message pop up when it was really cold at the beginning of the year. Haven't had it since.:shifty:
 
Lucky_Ls said:
I had that same message pop up when it was really cold at the beginning of the year. Haven't had it since.:shifty:
Click to expand...

That usually means that your brushes (in the alternator) are starting to fail.
 
Sorry guys busy day at work today. I am just now checking on the post. I am NOT one to disconnect the battery with the car running. These things habe 7 computers in them right? I will troubleshoot the harness when I get a chance. I am hoping that it is a circuit problem and not a generator issue. I hope I never have to change that alternator again!! I just think that it is wierd that the voltage regulates to 14.5 + - .1V under changing load (regulator and PCM working right?) but that it is still giving me the error message.
 
scjmc said:
Sorry guys busy day at work today. I am just now checking on the post. I am NOT one to disconnect the battery with the car running. These things habe 7 computers in them right? I will troubleshoot the harness when I get a chance. I am hoping that it is a circuit problem and not a generator issue. I hope I never have to change that alternator again!! I just think that it is wierd that the voltage regulates to 14.5 + - .1V under changing load (regulator and PCM working right?) but that it is still giving me the error message.
Click to expand...

The three circuits that I listed to check are specifically for the problem of charges (more or less) correctly but still gives an error light.
 
Thanks Joegr you are very helpful to a lot of members here with your tch knowledge.
 
hmmm

Just replaced my alternator for the second time in 6 months. The battery should read about 12 volts static, start the car,,,,the battery voltage should drop then return to normal if the alternator is working correctly,,,,turn on the a/c the reading should be 14.5 volts or so as the alternator is charging.....the only thing i can think of is your battery is not holding a charge,,,,,how old is it? Take it to Autozone and have it checked out.
 
Thanks for all the replies. Yes the battery checks out with a load tester. It is only about a year old motorcraft unit. I have not had time to look at the car again, so it has just been sitting in my driveway. I have been working a lot...
 
OK, here goes

Alternators on the V6 are easy to change. Not sure about the V8's. If you just changed the Alt. and you still get the fault light, then the Alt may be a bad one. Was it a rebuilt? or Brand new? Sounds like it is charging correctly. As soon as I put a new Alt on my V6 the light went out.
 
I have solved the problem. It turned out that the new alternator was defective (thanks NAPA) and was causing a communication problem with the PCM.
 
thanks Napa

I bought the autozone reman,,,,,it lasted 6 months then died. So they gave me a new one as replacement (not another reman) no extra charge. keep your receipts!
 
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