Amp gauges

[SUrban]

Amp gauge goes from charging to not charging. I stop turn off the motor for a minute, start it back up & it’s charging again. Drive for a few miles, then it does it again!
I did the 3 key thing, got a code 2502. Charging system output voltage.
Does that mean the Alternator is bad? And I need to replace it? or is it in the computer?
The truck only has 260,000 miles on it, original Alt.
I wish there was some place, to tell you where & how to fix these Codes!
Thanks for any & all help with this!

 

[Darkbloodmon]

I'd check the alternator itself at the output stud, the power wire, batteries, and cross over cables.

FWIW my 03's OEM alternator went out at 230K.

 

[Ozymandias]

With amp gauge you mean the lie-o-meter in the dash?

 

[SUrban]

With amp gauge you mean the lie-o-meter in the dash?

Yes! It charges at idle, then when I start driving & shifting gears it kicks off goes to zero.

 

[Ozymandias]

Put a real voltmeter on it and check if the voltage really goes to idle (battery voltage) when the dash does.
Mine did the same when the temp sensor under the driver's side battery failed.
Gauge showed Zero but the alternator kept charging just fine.

 

[SUrban]

In the last few days I’ve done a lot of reading & testing.
It turned out to be the Alternator was bad. Can’t really complain, since it had 262,000 miles on it. So I replaced it today, along with the original serpentine belt!
It works great!
Now on to the next problem! I have a warning on the IP, says “ Lamp Out “. And all of the lights work! Anyone want to give me an idea how to Fix It!
Thanks for all of the comments.

 

[Ozymandias]

Did you replace the boards in the taillights already?
Most of the time that's it.
Also the center brake light is monitored.

 

[SUrban]

Did you replace the boards in the taillights already?
Most of the time that's it.
Also the center brake light is monitored.

Yes, I replaced the tail light boards, and the 3rd brake light works!
This kind of stuff drives me crazy!