Chevrolet Silverado Turn Signal Bulb Size

Additional Notes

• The 4157NA bulb is a dual-filament T25 wedge type rated at 12V with a 27W high filament and 7W low filament, featuring natural amber glass rather than a coating. It appears across the Chevrolet Silverado front turn signal position from 2007-2012 as a universal fitment, and in 2003-2006 restricted to the 1500 trim in the front inner turn signal position.
• The 7443 and 7444NA bulbs share the same T20 wedge form factor and identical 12V, 21W/5W dual-filament ratings, with the 7444NA distinguished solely by its natural amber glass envelope. Both types are used across front and rear turn signal positions on the Silverado from 2015-2024, and the choice between them varies by model year and trim level rather than following a fixed pattern.
• The 7443 and 7444NA are not interchangeable in all positions on the Silverado. In the 2023-2024 model years, the front turn signal uses the 7443 on the 1500 and the 7444NA on the 2500/3500 HD, while the rear turn signal reverses that assignment, with the 7443 on the 2500 HD and the 7444NA on the 1500.
• The 3157NA and 3157 bulbs share the same T25 wedge body and 12V, 27W/7W dual-filament ratings, with the 3157NA carrying natural amber glass. On the Silverado, the 3157NA was used in the front turn signal position from 1999-2006, while the clear 3157 served the rear turn signal over the same 1999-2006 period.
• The 5702AK is a Sylvania-branded variant of the ANSI 3157 bulb with an amber coating applied externally rather than using natural amber glass. It was used in the Silverado 2500/3500 HD front turn signal position in 2013-2014, and in the 3500 HD only for 2009.
• The 3047 is a single-filament T25 wedge bulb rated at 12V and 27W, making it functionally distinct from the dual-filament 3157 it replaced in the rear turn signal position. The Silverado transitioned from the 3157 to the 3047 at the rear starting in 2007, with the 3047 remaining in use through 2013 and into 2014 on the 2500/3500 HD.
• The PY21W bulb uses a BAU15s offset bayonet base, which is physically incompatible with the wedge bases used by all other bulbs in these specifications. Its presence in the Silverado front inner turn signal from 1999-2002 is designated for export markets and reflects ECE regulatory standards rather than ANSI standards.
• The 12961, listed under the Philips part numbering system, is a T10 miniature wedge bulb rated at 12V and 5W with a single filament. It is used exclusively in the front outer side turn signal position on the Silverado, covering model years 2000-2006, with the 2003-2006 entries restricted to the 1500 trim.
• The 7444 is a clear dual-filament T20 wedge bulb rated at 12V, 21W/5W, sharing its physical and electrical characteristics with the 7443. On the Silverado, the 7444 was used in the rear turn signal from 2015-2018 and in the 1500 rear position in 2014, before the 7443 and 7444NA took over in subsequent years.
• Several front turn signal positions on the Silverado 1500 in 2016-2019 specify the 7443 only when HID headlamps are fitted, indicating that headlamp technology on those model years influenced which turn signal bulb was required in the front housing.