Suzuki Motorcycle DR-Z400S Turn Signal Bulb Size

Additional Notes

• The Suzuki Motorcycle DR-Z400S uses three distinct bulb types across its turn signal positions: the 12496, PY21W, and P21W. All three operate at 12 volts, making them consistent in electrical system requirements despite their differences in base type and light output characteristics.
• The P21W is an ECE-standard single-filament signalling bulb rated at 21 watts and fitted with a BA15s bayonet base. It produces clear white light and is not amber by design, which distinguishes it from the PY21W used in later model years.
• The PY21W shares the same 21-watt rating as the P21W but produces amber-tinted light inherently, achieved through a tinted glass envelope rather than an amber lens. It uses a BAU15s bayonet base, which is offset at a different angle than the BA15s base of the P21W, making the two bulbs physically non-interchangeable despite their identical wattage.
• The 12496 is a Philips/Osram part number designating a 12-volt halogen bulb for specialty applications. It appears across both front and rear turn signal positions on the DR-Z400S across multiple model years, making it the most frequently specified bulb type in these specifications.
• The BA15s and BAU15s bayonet bases differ in the rotational offset of their locating pins. The BA15s base used by the P21W has pins positioned symmetrically, while the BAU15s base of the PY21W has an offset pin arrangement. This physical difference prevents cross-installation between P21W and PY21W bulbs.
• The Suzuki Motorcycle DR-Z400S front turn signal used the P21W from 2000-2008, transitioned to the 12496 in 2009, then shifted to the PY21W for 2011-2013, before returning to the 12496 for 2014-2017 and 2019, with the PY21W again specified for 2018.
• The rear turn signal on the DR-Z400S followed a different pattern from the front across several years. For example, the 2015 rear position specifies a PY21W while the front specifies a 12496, and the 2012 rear position specifies a PY21W while the front also specifies a PY21W, indicating that front and rear fitments do not always share the same bulb type.
• Because the P21W, PY21W, and 12496 each carry distinct base configurations or application designations, substituting one for another without confirming socket compatibility and regulatory requirements for amber versus clear signalling output could result in an improper fitment for a given model year.