GMC Jimmy Back Up Light Bulb Size

The GMC Jimmy back up light utilizes 2456, P21W, 1156, and 199 bulb sizes depending on the specific version of the vehicle. Available data for the lighting components covers the range from 1973 to 2001.

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
2001	2456
1977-1997	1156
1976	199
1974-1975	1156
1973	199

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
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 GMC Jimmy model range, covering the 1974-1975 and 1977-1997 model years.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and produced to ANSI standards for the US and Canadian markets.
The BA15s bayonet base uses a single contact pin, which determines the physical mounting and electrical connection method in the lamp socket.
The 199 bulb is specified for the GMC Jimmy in the 1973 and 1976 model years and shares the same BA15s bayonet base, 12V rating, and 21W output as the 1156.
The 199 is classified as a variant of the 1156, meaning the two bulbs share core electrical characteristics, though they are distinct ANSI part numbers and may differ in physical construction.
Because the 199 and 1156 are separate ANSI designations, substitution between them warrants verification of socket and housing compatibility before installation.
The 2001 GMC Jimmy uses the 2456 bulb for the backup light, which represents a departure from the 1156-type bulbs used in earlier model years.
The 2456 is a festoon-style bulb, meaning it is cylindrical with end-cap contacts rather than a bayonet base, making it physically incompatible with sockets designed for the 1156 or 199.
The 2456 is rated at 12V and is designated for specialty applications under ANSI standards, applicable to both the US and Canadian markets.
The shift from a BA15s bayonet-base bulb in earlier Jimmy models to a festoon-type bulb in the 2001 model year indicates a socket design change that prevents direct interchangeability between the two bulb families.