Batt/ALT?

There are a couple things that we need to cover first.

When you say that the battery and alternator read good, are you load testing each?

Here are guides that help with this:

https://www.2carpros.com/articles/car-battery-load-test

https://www.2carpros.com/articles/how-to-check-a-car-alternator

If they both check out ok using these tests, then we are going to need to catch this with the light on so that we can find out what the output voltage is of the alternator.

Plus, we are going to have to find out what the voltage is on the alternator at pin I. This is the charge indicator and there is a resistor in the cluster that may be causing the light to come on incorrectly.

Have you ever experienced a drained battery, or has it always operated correctly?