Suzuki Motorcycle LT-Z400 QuadSport Z Tail Light Bulb Size

The Suzuki Motorcycle LT-Z400 QuadSport Z tail light requires a P21/5W bulb size for proper installation and function. Available information covers a specific time span from 2003 through 2014.

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
2012-2014	P21/5W
2003-2009	P21/5W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W

Other Locations

Additional Notes

The P21/5W is the sole tail light bulb type specified across all listed model years of the Suzuki Motorcycle LT-Z400 QuadSport Z, covering the 2003-2009 and 2012-2014 model years.
The P21/5W is a dual-filament bulb, meaning a single unit serves two distinct lighting functions, typically stop and tail, through separate filaments rated at 21W and 5W respectively.
The bulb operates on a 12V electrical system, consistent with standard 12-volt vehicle wiring.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement of the BAY15d base prevents incorrect installation orientation, ensuring the higher-wattage filament is connected to the correct circuit.
The P21/5W conforms to ECE (Economic Commission for Europe) standards, indicating it is recognized for use in European and worldwide markets under that regulatory framework.
Because the BAY15d base is specific to dual-filament applications, it is not interchangeable with single-filament bayonet bases such as the BA15s, despite a similar physical profile.