The Cadillac CTS brake light utilizes bulb sizes 2458 and 3157 for the lighting components. Data for the specified vehicle covers the period from 2003 through 2007.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Cadillac CTS uses the 3157 bulb for the brake light position across the 2003-2007 model years.
The 3157 is a dual-filament T25 wedge bulb rated at 12V with a 27W high filament and a 7W low filament, allowing it to serve both brake and running light functions within a single housing.
The 3157 conforms to ANSI standards applicable in both the United States and Canada.
The center high mount stop light on the 2004-2007 Cadillac CTS uses the PC168 bulb, while the 2003 model uses the PC175 for the same position.
Both the PC168 and PC175 are miniature T10 wedge bulbs fitted with a printed circuit board twist-lock socket, a design originally associated with instrument cluster applications.
The PC168 and PC175 are not interchangeable without confirming socket compatibility, as the twist-lock printed circuit board mount is a specific interface that differs from standard wedge sockets.
Both PC168 and PC175 operate at 12V and conform to ANSI standards for the United States and Canada.
The split between PC175 and PC168 at the 2003-to-2004 model year boundary indicates a mid-generation change in the center high mount stop light socket specification for the Cadillac CTS.