For the 2017 Cadillac ATS, the headlight bulb fitment depends on the factory headlight type. Models with halogen headlights use a 9012 bulb for both the low-beam and high-beam positions. Models equipped with HID headlights use a D3S bulb for both low beam and high beam. Confirm the headlight system before ordering, since 9012 and D3S applications are not interchangeable.
Other notable exterior lighting includes a 7444NA bulb for the front turn signal and parking light, a 921 bulb for the reverse light, and a 194NA bulb for the front side marker. The brake lights, center stop light, daytime running lights, tail lights, rear turn signals, and rear side markers are listed as LED applications.
- License plate: 2825 or 98
- Step and trunk lighting: 194 or 7441
- Interior lighting: 194 or 7441
- Vanity light: 7065