Chevrolet Biscayne Courtesy Bulb Size

The Chevrolet Biscayne courtesy light utilizes bulb sizes 89, 631, 211-2, and 90 depending on the specific application. Available information covers the span from 1958 through 1972.

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
1972	89
1967-1971	631
1966	211-2
1965	90
1964	631
1958-1963	89

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	89
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	631
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	211-2
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 13W.	90

Other Locations

Additional Notes

The bulb type 631 appears most frequently across the Chevrolet Biscayne courtesy bulb specifications, covering the 1964 and 1967-1971 model years. It is an ANSI-standard single-filament bulb with a BA15s bayonet base, rated at 12V and 21W.
The bulb type 89 is the second most recurring specification, used across the 1958-1963 and 1972 model years. It shares the same BA15s bayonet base as the 631 but operates at a lower wattage of 13W on a 12V circuit, making it a lower-wattage variant of the 1156 bulb family.
Both the 89 and 631 bulbs use the BA15s single-contact bayonet base, which means they are physically interchangeable in terms of socket fitment. However, their wattage ratings differ at 13W and 21W respectively, so substituting one for the other would alter the electrical load on the circuit.
The 1966 Biscayne uses the 211-2 bulb, a festoon-type unit with an SV8.5 base and a 41mm length, rated at 12V and 12W. This bulb type is physically distinct from the BA15s bayonet-base bulbs used in all other model years and is not interchangeable with them.
The 1965 Biscayne uses the bulb type 90, an ANSI-standard single-filament bulb with a BA15s bayonet base rated at 12V and 13W. Its wattage matches the 89, though the two carry different ANSI designations and are not confirmed as direct substitutes for one another.
Three distinct base types are represented across the full span of specifications: the BA15s bayonet base shared by the 89, 631, and 90 bulbs, and the SV8.5 festoon base used by the 211-2. A vehicle requiring a festoon-type bulb cannot accept a bayonet-base replacement without a socket adapter.
All bulb types listed in these specifications conform to ANSI standards applicable in both the United States and Canada, indicating consistent regulatory classification across the product range.
The wattage across all specified bulbs ranges from 12W to 21W, with the 631 drawing the highest current at 21W and the 211-2 drawing the lowest at 12W. This range reflects variation in the intended brightness output for the courtesy lighting function across different model years.