Lexus 1993 SC300 automatic transmission will not shift into overdrive?

If your 1993 Lexus SC300's automatic transmission is not shifting into overdrive, it could be due to several issues. Common causes include low Transmission Fluid levels, a faulty transmission control module, or a malfunctioning governor or speed sensor. It's also possible that there's a mechanical issue within the transmission itself. It's advisable to have a qualified mechanic diagnose the problem to ensure proper repairs.