Acura TL Turn Signal Bulb Size

Additional Notes

• The 7440 is the most consistently used bulb across the Acura TL's turn signal specifications. It serves as the rear turn signal bulb for nearly every model year in the dataset and also appears as the front turn signal bulb for the 1995-1998 model years. It is a single-filament T20 wedge bulb rated at 12V and 21W.
• The 7440 and 7443 share the same T20 wedge form factor, but they are not interchangeable. The 7443 is a dual-filament variant rated at 21W/5W, while the 7440 carries only a single filament at 21W. The Acura TL uses the 7443 exclusively for the front turn signal on the 2004-2006 model years.
• The 3457NA and 3357NA are both T25 wedge bulbs with natural amber glass, but they differ in filament count. The 3457NA is dual-filament (27W/7W) and was used in the front turn signal position on the 2012-2013 TL, while the 3357NA is single-filament (27W) and was used on the 2014 model year.
• Natural amber glass, denoted by the "NA" suffix in bulb designations such as 1157NA, 1034NA, 3457NA, and 3357NA, produces an amber color through the glass itself rather than through an amber-tinted lens or housing. This construction method is required in certain regulatory contexts to meet turn signal color standards.
• The 1157NA and 1034NA are both dual-filament bulbs sharing the BAY15d bayonet base with natural amber glass. The 1034NA is described as a variant of the 1157NA, with a slightly different wattage rating of 21W/5W compared to the 1157NA's 21W/5W, though the 1034NA is noted specifically as a variant designation within the same family.
• The front turn signal position on the Acura TL shows the widest variation in bulb types across its production span, drawing from five distinct bulb designations: 7440, 7443, 1157NA, 1034NA, 3457NA, and 3357NA. The rear turn signal position, by contrast, uses only the 7440 and 7507 across its full range of listed years.
• The 7507 bulb appears in the rear turn signal position on the 2002-2003 Acura TL, representing a departure from the 7440 used in surrounding model years for that position. The 7507 is a single-filament T20 wedge bulb, and its presence in those two years indicates a housing or circuit specification distinct from adjacent generations.
• The BAY15d bayonet base used by the 1157NA and 1034NA differs fundamentally from the wedge base used by the T20 and T25 bulbs in this specification set. BAY15d bulbs are retained by two offset pins and a twist-lock mechanism, making them physically incompatible with wedge-style sockets regardless of voltage or wattage similarity.
• The front turn signal on the 2011 Acura TL uses the 1034NA, a dual-filament BAY15d bulb, while the 2010 model uses the 1157NA, also a dual-filament BAY15d bulb. Both operate at 12V with a 21W/5W output, and the 1034NA is classified as a variant of the 1157NA, suggesting close but not guaranteed interchangeability depending on socket tolerances.
• Across the full specification set, all listed bulbs operate at 12V, which is consistent with standard automotive electrical systems. Wattage varies by filament configuration, with single-filament bulbs in this set rated at either 21W or 27W, and dual-filament bulbs rated at combinations such as 21W/5W or 27W/7W, reflecting their use in circuits that serve both signaling and secondary indicator functions.