When upgrading the stock halogen / incandescent lamps to led lighting bulbs, the bulb size guide will be much helpful, below are the bulb size guide for 2013~ 2017 Cadillac ATS; yet it is for reference only, it is suggested to check the owner manual to confirm the bulb size guide is correct before purchasing.
- High Beam Headlight for the model with halogen capsule headlamp: 9012; for with HID headlamps: D3S
- Low Beam headlight for the model with halogen capsule headlamp: 9012; for with HID headlamps: D3S
- Front turn signal light ( blinker light ): 7440NA / 7444NA / 7440A / 7443-SCK
- Rear turn signal light : LED
- Brake Light / Tail Light: LED
- Back-up reverse light: 921
- License plate light / Tag light: 2825 / 2825L
- 3rd Brake light/ Center high mount stop light: LED
- Front side marker light: 194 ; for Rear side marker light: LED
- Trunk / Cargo Area light: 175
- Stepwell light: 175
- Vanity mirror light: 7065
- Interior door light: 175
