Chevrolet Blazer Back Up Light Bulb Size

The Chevrolet Blazer back up light utilizes bulb sizes 1156, 199, 921, 2356, 2456, 3156, and P21W. Data for the specified vehicle components covers the range from 1969 to 2022.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
2022	921
2019-2020	921
2003	2456
2002	2356
1999-2001	3156
1998	2356
1995-1997	1156
1993-1994	2456
1992	2356 (With Halogen Capsule Headlamps)
1992	1156 (With Sealed Beam Headlamps)
1987-1991	1156
1973-1974	199
1971-1972	1156
1969-1970	199

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2356
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	199

Other Locations

Additional Notes

The 1156 bulb is the most frequently specified backup light bulb across the Chevrolet Blazer lineup, appearing in model years 1987-1992 (with sealed beam headlamps in 1992), 1995-1997, and 1970-1972. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W.
The 199 bulb shares the same BA15s bayonet base, single-filament construction, and 12V, 21W rating as the 1156, and is classified as a variant of it. The Blazer uses the 199 in 1969-1970 and 1973-1974.
The 3156 is a single-filament wedge bulb in a T25 form factor, rated at 12V and 27W. It is specified for the Blazer in 1999-2001, making it a higher-wattage alternative relative to the 1156 used in earlier years.
The 921 is a wedge bulb in a T15 form factor, rated at 12V and 16W. It is specified for the Blazer in 2019-2020 and 2022, and carries a lower wattage than both the 1156 and 3156 types used in prior generations.
The 2356 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V. Its dual-filament design distinguishes it from the single-filament 1156 and 3156 types, and it is specified for the Blazer in 1992 (with halogen capsule headlamps), 1998, and 2002.
The 1992 Chevrolet Blazer is the only model year in these specifications where two different backup light bulb sizes are listed, with the 2356 applying to vehicles equipped with halogen capsule headlamps and the 1156 applying to those with sealed beam headlamps.
The 2456 is a festoon-type bulb designated for specialty applications, rated at 12V with no wattage specified. It is listed for the Blazer in 1993-1994 and 2003.
The BAY15d base of the 2356 and the BA15s base of the 1156 and 199 are physically incompatible despite their similar bayonet-style mounting, as the BAY15d features offset pins to accommodate its dual-filament design.