The INFINITI QX4 brake light components utilize 1157, 7440, and 7443 bulb sizes for various lighting applications across the different trim levels. Available data for the specified vehicle covers the period from 1997 through 2003.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The INFINITI QX4 brake light specifications cover model years 1997 through 2003, with bulb requirements varying across that production span.
The 7440 is a single-filament T20 wedge bulb rated at 12V and 21W, conforming to ANSI standards for the US and Canadian markets. It serves as the brake bulb for the QX4 across the 2001-2003 model years.
The 1157 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21W/5W filament configuration. Its dual-filament design allows it to serve both brake and running light functions from a single unit. It is the brake bulb for the 1997-1998 QX4.
For the 1999-2000 INFINITI QX4, brake bulb fitment is conditional on headlamp type. Vehicles equipped with halogen capsule headlamps use the 1157, while those equipped with HID headlamps use the 7443.
The 7443 is a dual-filament T20 wedge bulb rated at 12V and 21W/5W, sharing the same wattage profile as the 1157 but using a wedge base rather than a bayonet base. The two bulbs are not interchangeable due to this base difference.
Although the 7440 and 7443 share the T20 wedge form factor and the same 21W primary filament rating, the 7440 carries only a single filament while the 7443 carries two. This distinction makes them non-interchangeable in applications where dual-filament operation is required.
The 168 is a miniature T10 wedge bulb rated at 12V and 4.9W, conforming to ANSI standards. It serves as the center high mount stop light bulb on the QX4 for all model years from 1997 through 2003.
The center high mount stop light specification for the QX4 remains unchanged across the entire 1997-2003 production run, with the 168 bulb applying uniformly regardless of model year or headlamp configuration.
All bulb types listed in the QX4 brake specifications conform to ANSI standards applicable to both the United States and Canadian markets.
The shift from the 1157 bayonet-base bulb to the 7440 wedge-base bulb between the 2000 and 2001 model years represents a change in socket type, meaning the two bulbs are physically incompatible with each other's housings.