Possible lamp failure sensor is causing this concern.
*Hands-on* testing by qualified personnel will be required.
Keep in mind that a poor connection or old and tired bulb can cause this issue as well..
Many times it is very easy to overlook a malfunctioning bulb..
Good luck!
RepairPal Certified shops can diagnose and repair your 1992 Lexus SC400. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
CLOSELY Inspect ALL of the bulbs ‘at night’ - compare right and left sides to see if same illumination is present on both - is one side brighter..