GMC Acadia Dome Light Bulb Size

Additional Notes

• The GMC Acadia dome light bulb specifications reference two distinct bulb types across the model's production years: the 12961 and the 212-2.
• The 212-2 is an ANSI-standardized festoon bulb with an SV8.5 base and a 41mm length, rated at 12V and 12W. It is the specified dome light bulb for the GMC Acadia across the 2007-2016 model years.
• The 12961 is a Philips miniature wedge bulb of the T10 type, fitted with a W2.1x9.5d base and rated at 12V and 5W. It is specified for the 2020, 2021, and 2023 model years of the GMC Acadia.
• The festoon and wedge bulb types use fundamentally different base designs and are not interchangeable. The SV8.5 festoon base is a cylindrical end-cap style, while the W2.1x9.5d wedge base relies on wire contacts pressed into a plastic wedge.
• The 212-2 draws 12W, whereas the 12961 draws 5W. This difference reflects a change in the power requirement between the earlier and later Acadia generations.
• The 12961 designation is a Philips-specific part number rather than an ANSI industry standard, which means equivalent bulbs from other manufacturers are typically cross-referenced by their T10 type and W2.1x9.5d base specification.
• The 212-2 festoon format is a widely used North American standard, making it broadly available across automotive and retail supply channels in the US and Canada.
• Because the two bulb types differ in base design, wattage, and physical format, substituting one for the other in a given model year would not produce a correct fitment.