The cluster brightness is controlled over the LIN bus by the steering control module (clockspring) which is physically and electrically attached to the left multifunction switch module (lighting control stalk).
If you still have the warranty, let the dealer fix it. If not, you better get the factory service manual before you mess with it so you know how to disable the airbags.
08 4 Door Rubicon
Member of Two Trackers 4wd Club
Great Lakes Four Wheel Drive Association
United Four Wheel Drive Associations