As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE DISPLAY UNITS, PILOT'S PRIMARY FLIGHT DISPLAY, COPILOT'S PRIMARY FLIGHT DISPLAY AND COPILOT'S NAV DISPLAY DIMMED OUT OF VIEW DURING CRUISE AT FL240. PILOT REPORTED THAT DIMMING WAS AFFECTED BY OPERATION OF CABIN HEAT. FOUND TAPER BLOCK (TB4) TO HAVE LOOSE PINS. THIS IS A DISTRIBUTION BLOCK FOR AIRCRAFT LCD DIMMING.