Greetings!

I have to ask just to make certain. Are you doing any kind of force AC or other hijack setting that might make your player think it is on AC power? You have the dimmer control settings available, correct?

One place to check would be the illumination line going to the player / sled harness. Verify that it is changing appropriately when the lights are on. Perhaps you have a loose connection (or no connection) on that wire.

Is there someone nearby with a player installation that you can test your player in, to eliminate the car installation or the player as the source of the problem?