1999 Lexus LS 400 instrument panel lighting

Suddenly my instrument dash backighting (tach, speedometer, etc.) Only works when the "day lights" are on---in other words when I roll the turn/light stick to turn on the headlights (either auto-offhigh beam or not) the backlight on the tach, speedometer, fuel gauge, etc. Goes black. When I turn lights off and only the safety headlights are on, the panel lights up again? When it is black, the only green lights on the panel are the symbol for "headlights on", the "D" for Drive gear, and the "Cruise"(when I put cruise cntl on) are illuminated. Rest is totally black!