I have a 2007 HR Imperial ISL 400 Cummins that is showing a red battery light on the air leveling system at the drivers side controls.
My alternator is charging at 13.9 amps at idle, and 13.5 at 2000 RPM's. Do I need to get alternator checked, check belt tension, or is it the batteries? Chassis batteries are 2 years old.
Thanks