Check whether the auto light control function is normal.(1) Set the combiner to the OPEN state. (After starting the engine or turning the ignition switch ON, operate the HUD ON/OFF switch.)
(2) Cover the illuminance sensor section by hand.OK: Darkens (Combiner display area)
(3) Remove the hand from the covered illuminance sensor section.OK: Brightens (Combiner display area)
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ). Replace the HUD.