2018 GEM Battery indicator keeps reading full

[Gary B.]

Hoping for some help please. The battery indicator reads full all the time even after we drive it to the point that the batteries are depleted. We tried removing the power, and the fuse and the indicator goes all the way down but then automatically keeps going back up to full again. We tried another battery indicator gauge from another vehicle which is  the same year Gem and that didn't do anything different. Shouldn't the controller see the voltage going down and report that to the battery indicator gauge. Can't figure out why this is happening. Any advice? Thank you.