The Lexus SC400 back up light requires bulb sizes 7440, 1156, or P21W depending on the specific production period. Data for the lighting components covers the range from 1992 to 2000.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Lexus SC400 uses two distinct bulb types across its back up light positions: the 7440 and the 1156 for the standard back up light, and the 7443 for the inner back up light on certain model years.
The 1156 bulb is a single-filament type with a BA15s bayonet base, rated at 12V and 21W. The bayonet base uses a twist-and-lock mounting style, which is physically incompatible with the wedge-style base found on the 7440 and 7443 bulbs.
The 7440 is a single-filament T20 wedge bulb rated at 12V and 21W. The T20 designation refers to the wedge base form factor, which differs from the BA15s bayonet base of the 1156 despite both bulbs sharing the same 12V, 21W electrical rating.
The 7443 is a dual-filament T20 wedge bulb rated at 12V with a 21W primary filament and a 5W secondary filament. Its dual-filament construction makes it electrically distinct from the single-filament 7440, even though both share the T20 wedge base form factor.
Because the 7440 and 7443 share the same T20 wedge base, physical fitment between the two is possible, but substituting one for the other would result in incorrect wattage output on one or both circuits due to the filament difference.
The Lexus SC400 back up light transitioned from the 1156 bayonet-base bulb to the 7440 T20 wedge bulb between the 1996 and 1997 model years, representing a base-type change that makes the two bulbs non-interchangeable.
The 1996 SC400 inner back up light specifies the 1156 bulb with a production cutoff noted as "To 08/1996," indicating that vehicles produced after that date within the same model year may use a different specification.
All three bulb types listed across these specifications, the 7440, 1156, and 7443, conform to ANSI standards applicable in both the United States and Canada.
The 1992-1996 SC400 back up light uses the 1156 bulb, while the 1997-2000 model years use the 7440. These two bulbs are not interchangeable due to the difference in base type.
The inner back up light position is specified only for the 1995-2000 SC400, using the 1156 for 1995 and part of 1996, and the 7443 for 1997-2000.