The Lexus GS300 brake light utilizes 7443 and 1157 bulb sizes depending on the specific production period for the vehicle. Provided information covers the span from 1993 through 2004.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 7443 and 1157 bulbs are the most frequently specified types across the Lexus GS300 brake lighting positions. Both are dual-filament bulbs rated at 12V with a 21W/5W output, where the higher wattage filament activates under braking and the lower wattage filament serves a secondary function such as a tail light.
Despite sharing identical wattage ratings of 21W/5W at 12V, the 7443 and 1157 are not interchangeable. The 7443 uses a T20 wedge base, while the 1157 uses a BAY15d bayonet base, meaning the two types require physically different sockets.
The Lexus GS300 brake bulb specification shifts from the 1157 to the 7443 between the 1997 and 1998 model years across the main brake light position, reflecting a base type change while the electrical output remained the same.
For the 1997 Outer Brake and Inner Brake positions, the specification carries a "To 08/1997" notation alongside the 1157 bulb, indicating a mid-year production change within that model year.
The Center High Mount Stop Light position on the GS300 uses lower-wattage miniature bulbs compared to the main brake positions. The 168 bulb is a T10 wedge type rated at 12V and 4.9W, and it is specified for model years 1998-2004.
The 194 bulb, specified for the 2005 Center High Mount Stop Light, is also a T10 wedge type but is rated at 3.78W, making it a lower-output variant than the 168. Although both share the same T10 wedge form factor, their wattage ratings differ and the two are not always considered equivalent replacements.
The 921 bulb, a T15 wedge type rated at 12V and 16W, is specified for the Center High Mount Stop Light on the GS300 from 1993-1997. It is a single-filament bulb and operates at a notably higher wattage than the T10 types used in later model years.
All bulb types listed across the GS300 brake specifications conform to ANSI standards applicable in the United States and Canada, indicating standardized dimensional and electrical tolerances within those markets.
The Inner Brake sub-part position is specified only for model years 1996-2000, while the Outer Brake position extends across a broader range from 1995-2005, suggesting a difference in how brake light assemblies were structured across certain production periods.
The 7443 T20 wedge base and the 1157 BAY15d bayonet base represent the two distinct socket families present throughout the GS300 brake lighting specifications, and correct socket compatibility is a necessary condition for proper fitment in each position.