Acura TLX front turn signal bulbs use 12174SV size while rear turn signal bulbs use 7440 size. The replacement bulb chart covers 2015 to 2020 model years with corresponding specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Acura TLX front turn signal uses the 12174SV bulb across the 2015-2018 model years.
The 12174SV is a Philips SilverVision part number, designating a halogen bulb with an enhanced coating that alters the light output appearance, rated at 12V.
The rear turn signal on the Acura TLX uses the 7440 bulb across the 2015-2020 model years.
The 7440 is an ANSI-standardized bulb designation recognized in the United States and Canada, which means it conforms to a defined set of electrical and physical characteristics shared across manufacturers.
The 7440 is a single-filament wedge-style bulb in the T20 form factor, rated at 12V and 21W.
A single-filament construction means the 7440 serves one lighting function only, as opposed to dual-filament bulbs that handle two functions such as turn signal and brake light within a single housing.
The front and rear turn signals on the TLX use different bulb types, meaning the two positions are not interchangeable with each other despite both operating on 12V systems.
The 7440 rear turn signal fitment spans a longer production range than the 12174SV front fitment, covering six model years compared to four.