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 2003~ 2017 Cadillac CTS; 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 2003~2007 Cadillac CTS: 9005XS ; for 2008~2014 Cadillac CTS with halogen capsule headlamp: H9; for 2008~2014 Cadillac CTS with HID capsule headlamp & 2015~16 CTS: D1S
- Low Beam headlight for 2003~2007 Cadillac CTS with halogen capsule headlamp: 9006XS; D1S with HID for 2008~2014 Cadillac CTS with halogen capsule headlamp: H11; DIS with HID
- Fog light for 2003~2007 Cadillac CTS: 9145; for 2008~2015 Cadillac CTS: H11LL / H11
- Front turn signal light ( blinker light ) for 2003~2007 Cadillac CTS: 3157 / 3157K / 3157-SCK for 2008~17 Cadillac CTS: 12272NA / 12188
- Rear turn signal light /Brake Light / Tail Light for 2003~2007 Cadillac CTS: 3157 / 3157K / 3157-SCK for 2008~2017 Cadillac CTS: LED
- Back-up reverse light for 2003~2007 Cadillac CTS: 3157 / 3157K / 3157-SCK; for 2008~2013 Cadillac CTS: LED ;for 2014~2017 Cadillac CTS Sedan model: 921 ; for Coupe model: LED
- License plate light / Tag light: 2825 / 2825L
- Interior Map light: PC175
- Interior Dome light: PC175 / 2825
- Trunk / Cargo area light: 211-2
- 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: 2886X
- Vanity mirror light: 6612F
- Interior door light: 906
Vehicles includes: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Cadillac CTS
