Honda Motorcycle VT500C Shadow Turn Signal Bulb Size
Honda Motorcycle VT500C Shadow front turn signal bulbs measure 1034 in size, while rear turn signal bulbs measure P21W or 1073, with each bulb size corresponding to specific lighting positions on the motorcycle. The replacement chart covers 1983 to 1986 model years and documents bulb size specifications across the vehicle production range.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Honda Motorcycle VT500C Shadow uses two distinct bulb types across its front and rear turn signal positions, with the 1034 appearing in all four model years for the front position and P21W and 1073 appearing across the rear position.
The 1034 is an ANSI-standard dual-filament bulb rated at 12V and 21/5W, fitted with a BAY15d bayonet base, and is classified as a variant of the more widely known 1157.
The BAY15d base used by the 1034 features two offset pins at different heights, which physically prevents it from being inserted into a single-filament BA15s socket, making it incompatible with P21W and 1073 housings.
The P21W is an ECE-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and is used in markets across Europe and worldwide.
The 1073 is an ANSI-standard single-filament bulb rated at 12V and 13W, also fitted with a BA15s bayonet base, and is described as a lower wattage variant of the 1156.
Although the P21W and 1073 share the same BA15s base type, their wattage ratings differ substantially, at 21W and 13W respectively, which means substituting one for the other would alter the electrical load on the turn signal circuit.
For the Honda Motorcycle VT500C Shadow, the rear turn signal position used the 1073 exclusively in the 1985 model year, while the 1983, 1984, and 1986 model years used the P21W in that same position.
The front turn signal position remained consistent across the full 1983-1986 production span, with the 1034 specified for all four years without variation.
The dual-filament nature of the 1034 means it carries two separate wattage ratings, 21W and 5W, corresponding to two independent circuits within a single bulb envelope, a characteristic absent from both the P21W and the 1073.
The ANSI and ECE standards represent separate regulatory frameworks, and bulbs designated under one standard are not automatically interchangeable with those designated under the other, even when base types appear similar.