GMC General Back Up Light Bulb Size

The GMC General back up light utilizes a 1073 bulb size for illumination purposes. Data for the specific component covers the range from 1984 through 1988.

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
1984-1988	1073 (Tiltmaster)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	1073

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Additional Notes

The 1073 is the sole back up light bulb size listed across all specified GMC Tiltmaster model years, covering 1984-1988.
The 1073 bulb follows the ANSI standard, meaning it conforms to a recognized North American specification valid in both the United States and Canada.
The 1073 operates on a 12-volt electrical system and draws 13 watts, placing it in the range typical of standard incandescent automotive signal and utility lamps.
The 1073 uses a BA15s bayonet base, which is a single-contact bayonet mount. The "s" designation indicates a single center contact at the base, as opposed to a dual-contact variant.
The 1073 is a single-filament bulb, meaning it serves one lighting function only, which is consistent with its application as a dedicated back up light.
The 1073 is described as a lower wattage variant of the 1156. While the two bulbs share the BA15s bayonet base, the wattage difference means they are not directly interchangeable without accounting for the electrical load difference in the circuit.