GMC Repair: Battery not charging, gmc envoy xl, gmc envoy

Question
I have 2003 GMC Envoy XL and keep getting "battery not charging" message in display. Battery is brand new, less than a week old and I recently had alternator checked. Could the problem be the aux battery? What is best way to isolate what is causing this problem?

Answer
Hi
I do not see an Aux. battery in this vehicles system or schematics.
If it was installed aftermarket,due to a sound system or other electronics,  I cannot help you. If you remove it all and the light still comes on, I'll be MORE than happy to assist you.
Basic checks.... Alternator output @ battery when light on
Alternator output at alternator when light on
should both be close to same
make sure the PCM is turning on the alternator (This alternator system is TOTALLY controlled by the PCM)
I hope this helps
awl