Pontiac Aztek Back Up Light Bulb Size

The Pontiac Aztek back up light requires bulb sizes 3155 and 2355 for the rear exterior lighting system. Data for the specific components covers the period from 2001 through 2005.

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
2005	3155
2004	2355
2001-2003	3155

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3155
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2355

Other Locations

Additional Notes

The 3155 is a single-filament wedge bulb in the T25 form factor, rated at 12 volts and 27 watts, and conforms to ANSI standards applicable in both the United States and Canada.
The 2355 is a dual-filament bulb with a BAY15d bayonet base, rated at 12 volts, and also conforms to ANSI standards for the United States and Canada.
The Pontiac Aztek uses the 3155 bulb for the back up light across the 2001-2003 and 2005 model years.
The 2004 Pontiac Aztek departs from the otherwise prevalent 3155 fitment, instead specifying the 2355 bulb for the back up light position.
The 3155 and 2355 are not interchangeable. The 3155 uses a wedge base, while the 2355 uses a BAY15d bayonet base, meaning the two bulbs require physically different sockets.
A further distinction between the two bulbs is filament count. The 3155 is a single-filament design, whereas the 2355 carries dual filaments, which reflects a difference in intended electrical function.
The BAY15d base of the 2355 is an offset twin-contact bayonet fitting. The offset pin arrangement prevents incorrect insertion of a bulb with a different pin configuration into the same socket.
Because the 2004 model year specifies a dual-filament bulb while surrounding model years specify a single-filament bulb, substituting a 3155 into a 2004 Aztek back up light socket would be an incorrect fitment regardless of any physical adapter considerations.