Harley-Davidson FLHTCU Electra Glide Ultra Classic Turn Signal Bulb Size

Harley-Davidson FLHTCU Electra Glide Ultra Classic rear turn signal bulb uses a P21W size. The replacement chart covers 2012 to 2013 vehicle production years with bulb size specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Rear Turn Signal

Years	Bulb Size
2012-2013	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The P21W is the rear turn signal bulb used in the Harley-Davidson FLHTCU Electra Glide Ultra Classic for the 2012-2013 model years.
The P21W follows the ECE (Economic Commission for Europe) standard, which is a regulatory framework governing lighting equipment used across Europe and numerous other markets worldwide.
As a single-filament bulb, the P21W is dedicated solely to one lighting function, distinguishing it from dual-filament bulbs that serve two functions such as braking and signalling simultaneously.
The P21W operates at 12 volts and consumes 21 watts, a wattage level typical for turn signal applications where brightness and visibility are required.
The BA15s bayonet base is a single-contact bayonet fitting, and the "s" designation indicates a single contact point at the base, which is a critical fitment detail when sourcing a replacement bulb.
The BA15s base is not interchangeable with the BA15d base, which carries two contact points and is used in dual-filament applications, making base type verification essential before installation.