Scion xA brake bulbs use 7443 size for outer and standard brake applications, while the center high mount stop light requires 168 size bulb. The replacement chart covers 2004 to 2006 vehicle production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Scion xA uses two distinct bulb types across its brake lighting system for the 2004-2006 model years: the 7443 and the 168.
The 7443 is a dual-filament wedge bulb in the T20 form factor, rated at 12V with a 21W/5W output, conforming to ANSI standards for the US and Canada markets. The dual-filament design allows a single bulb to serve both a high-intensity brake function and a lower-intensity running light function.
The 168 is a single-filament miniature wedge bulb in the T10 form factor, rated at 12V and 4.9W, also conforming to ANSI standards for the US and Canada markets. Its lower wattage reflects its role as an indicator rather than a primary brake signal source.
In the Scion xA, the 7443 is specified for the outer brake lights across all three model years, while the 168 is specified exclusively for the center high mount stop light.
The T20 and T10 designations refer to the physical wedge base sizes of the respective bulbs, and these two form factors are not interchangeable with each other despite both using a wedge-style base.
The 7443 and the physically similar 7440 single-filament bulb share the same T20 base, but substituting a 7440 for a 7443 in the outer brake position would result in the loss of one filament's function.