B737 Master Lights Test and Dim Switch

TEST – illuminates all system lights on forward and aft overhead panels, and some lights on Captain and First Officer main panels to full brightness.

BRT (bright) – sets all system lights on forward and aft overhead panels, and some lights on Captain and First Officer panels to full brightness.

DIM – sets all system lights on forward and aft overhead panels, and some lights on Captain and First Officer panels to low brightness.

Note: Placing the Master Lights Test and Dim Switch in the TEST position will result in a master caution recall and any stored fault will cause the associated light to remain illuminated when the switch is released.