GMC Sierra Side Marker Bulb Size

Additional Notes

• The 194 bulb is the most widely used size across the GMC Sierra's side marker specifications. It is an ANSI-standard miniature wedge bulb in the T10 form factor, rated at 12V and 3.78W, and it covers the front side marker position across all listed model years from 1999-2018.
• The T10 wedge form factor is shared by three of the four bulb types listed in these specifications: the 194, the 12961, and the PC161. Despite sharing the same physical envelope, these bulbs are not interchangeable due to differences in base type, wattage, and socket design.
• The 12961 is identified by a Philips part number rather than an ANSI designation. It uses a W2.1x9.5d base and is rated at 12V and 5W, giving it a higher wattage output than the 194 at 3.78W. It appears exclusively in the rear side marker position on Sierra 3500 HD trims from 2007-2014.
• The 7443 is a dual-filament T20 wedge bulb rated at 12V with a 21W/5W output, making it substantially more powerful than the other bulbs in these specifications. Its dual-filament design means it serves two distinct brightness levels within a single housing.
• The PC161 carries an ANSI standard designation but is noted as a miniature T10 wedge bulb with a printed circuit board twist-lock socket, a base type associated with instrument cluster applications. It is listed for the 2007 GMC Sierra 1500 rear side marker position only.
• The rear side marker position shows significantly more variation in bulb size across trims and years than the front. The front side marker uses the 194 exclusively across all listed years, while the rear draws from four distinct bulb types depending on the model year and trim level.
• For the 2014 GMC Sierra, the rear side marker bulb size differs by trim: the 1500 uses a 194, while the 3500 HD requires a 12961. These two bulbs share the T10 form factor but have different bases, so they are not interchangeable despite the physical similarity.
• The 2016 front and rear side marker entries both carry a 1500-only notation, meaning the 194 specification for that year is confirmed only for that trim in the available data.
• The 2020 rear side marker entry applies solely to the Sierra 3500 HD and specifies the 7443, a bulb type that does not appear in any other year within these specifications. The 2019 3500 HD rear side marker, by contrast, uses the 194.
• The 2007 Sierra rear side marker is the only year in these specifications where two different non-194 bulb types are listed simultaneously across trims, with the 1500 using the PC161 and the 3500 HD using the 12961.