When we are driving the radio and odometer lights dim. The switch to control the lights is all the way up to the brightest setting. It stays like that for a while and then comes back on brighter. We have taken to the dealer and it doesn't do it then. They have no idea why it does this.
Is there anything that might be impeding the sensor located on the dash, it reads ambient light, and if headlights are set to auto illuminate it dims dash light when activated.
They have a system that automatically adjusts the charging output to the voltage needs of the vehicle. I would start with that particular sensor as a possible culprit when trying to find the issue.