GMC Sierra Courtesy Bulb Size

Additional Notes

• The GMC Sierra uses three distinct courtesy bulb types across its model years: the 212-2, the 194, and the 74, each representing a different bulb format and wattage rating.
• The 212-2 is a festoon-style bulb with an SV8.5 base and a 41mm length, operating at 12V and 12W. Its festoon format means it is held in place by spring-loaded end caps rather than a socket, which is a different retention method than wedge-base bulbs.
• The 194 is a T10 miniature wedge bulb rated at 12V and 3.78W. The wedge base is self-retaining and does not use a separate socket pin, making it a common format in low-current interior lighting applications.
• The 74 is a T5 miniature wedge bulb rated at 12V and 1.4W. At 1.4W, it draws considerably less power than the 194 and 212-2, reflecting its use in lower-intensity lighting positions.
• All three bulb types conform to ANSI standards applicable in both the United States and Canada, indicating standardized electrical and physical specifications across North American markets.
• The 212-2 is the most frequently specified courtesy bulb in the GMC Sierra lineup, covering model years 2007-2014 across applicable trims.
• For the 2014 GMC Sierra, the 212-2 courtesy bulb specification applies exclusively to the 3500 HD trim. Other Sierra variants for that year are not covered under this specification.
• The 2007 Sierra carries an additional qualifier, noting the 212-2 as a rear courtesy bulb for the 3500 HD only, distinguishing it from a general cabin application.
• The courtesy bulb specification shifted from the 194 to the 212-2 between the 2006 and 2007 model years for applicable trims, representing a change in both bulb format and wattage from 3.78W to 12W.
• The 74 and 194 are both wedge-base bulbs, but their T5 and T10 designations indicate different physical sizes, meaning the two types are not interchangeable despite sharing the same base style.