Chevrolet Malibu Dome Light Bulb Size

Additional Notes

• The Chevrolet Malibu dome light draws from four distinct bulb families across its production history: the miniature wedge T10 (12961), the festoon types (561, 562, and 211-2), the dual-filament bayonet 1004, and the single-filament bayonet 631.
• The 561 festoon bulb is the most frequently specified type across the Malibu's dome light history, covering model years 1974-1975, 1978-1979, 1982-1983, and 1997-2004.
• The 12961 is a Philips-designated miniature wedge bulb with a T10 form factor and W2.1x9.5d base, rated at 12V and 5W. It is the specified dome bulb for the Chevrolet Malibu from 2016 through 2024, excluding 2022.
• The 561 and 562 are both 44mm festoon bulbs with end-cap contacts rated at 12V and 12W. Despite their near-identical physical and electrical characteristics, they carry separate ANSI designations and are not listed interchangeably within these specifications.
• The 211-2 is a festoon bulb with an SV8.5 base and a 41mm length, rated at 12V and 12W. Its slightly shorter length compared to the 561 and 562 makes it a distinct fitment, as festoon bulbs rely on physical length to maintain contact within their holders.
• The 1004 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21/5W output. It is described as a variant of the 1157 and was specified for the Malibu dome light in 1980-1981, an atypical application given that dual-filament bulbs are more commonly associated with stop and tail lamp functions.
• The 631 carries a BA15s single-contact bayonet base and is rated at 12V and 21W. It is described as a variant of the 1156 and was specified solely for the 1966 model year dome light, making it the rarest fitment in these specifications.
• Festoon bulbs depend on physical length for proper contact, meaning the 41mm 211-2 and the 44mm 561/562 are not interchangeable despite sharing the same voltage and wattage ratings.
• The bayonet-base bulbs, the 1004 (BAY15d) and the 631 (BA15s), use mechanically distinct bases. The BAY15d base has offset pins to prevent incorrect installation of a dual-filament bulb, while the BA15s base uses a single-contact design, making these two types physically incompatible with each other's sockets.
• The T10 wedge base of the 12961 is mechanically and electrically incompatible with the festoon and bayonet holders used in earlier Malibu model years, as the wedge type relies on blade contacts rather than end-caps or bayonet pins for its electrical connection.