Product Specifications

ITEM	VOLTAGE	WATTAGE	BASE	CERT
H15	12V	15/55W	PGJ23T-1	E4
	24V	20/60W	PGJ23T-1	E4

I. Origin & Evolutionary Position
The H15 (PGJ23T-1) is a pioneering model in the intelligent evolution of automotive lighting, representing a key transition from traditional single-function lighting to integrated auxiliary照明. It was widely used in a vast number of mainstream European, Japanese, and American models from the early to mid-2000s (e.g., specific years of Volkswagen, Audi, Toyota, Honda, Ford), enabling the "low beam + integrated front fog lamp" design within a single headlight unit. Its design初衷 was to meet the dual needs of regulated main lighting and adverse-weather auxiliary lighting within a compact space using a dual-filament structure inside a single bulb, without adding extra lamp units.

II. Core Function: Integrated Low Beam & Fog Lamp

1. Classic Dual-Filament分工:

   • Main Filament (typically 55W): Serves as the standard low beam, providing the primary road illumination compliant with safety regulations.

   • Auxiliary Filament (typically 15W or 21W): Serves as the integrated front fog lamp. When the driver activates the front fog light switch, this filament illuminates independently, emitting a warmer, more penetrating light specifically designed to illuminate the wide-angle area close to the front of the vehicle in rain or fog.

2. Paragon of Space Integration: This design eliminated the need for a separate fog light housing in the vehicle's front bumper, simplifying design and unifying aesthetics with functionality.

III. Product Features & Key Identification

• Signature Base: PGJ23T-1: This is the gold standard for identifying this version of H15. It is a special bayonet base featuring three tabs (the "T" stands for Three-Tab) with a central square alignment slot. This combination of "three tabs + central square slot" is its unique characteristic.

• Highly Vehicle-Specific: Its base design and electrical logic (dual filaments with common or independent ground) are precisely matched to specific headlight assemblies and vehicle wiring. It must never be replaced with visually similar single-filament bulbs (e.g., H11) or other dual-filament bulbs (e.g., H4, H13).

• Precise Optical Alignment: The central square slot on the base ensures the bulb can only be installed in the socket at one correct angle, guaranteeing both the low beam and fog light beams are projected onto their intended areas.

Important Notes & Selection Guide

• Primary Application: Used in vehicles with "separated high/low beams" that integrate the fog lamp into the low beam reflector. A common configuration is: two separate front headlight units (one for combined high/low beam like H4, and the other for low beam/fog lamp combination, i.e., H15).

• Distinction from Later H15 (5-Pin): The PGJ23T-1 base H15 is an early mechanical version for "Low Beam + Fog Lamp". The later 5-pin (PGJ25-1) H15 is an electronic version often for "Low Beam + Cornering Light". They are not interchangeable.

• Identification Methods:

  1. Inspect the Base: Remove the old bulb and confirm the base has three plastic tabs and a distinct central square slot.

  2. Inspect the Contacts: The bulb base typically has three metal contacts (main filament, auxiliary filament, common ground).

  3. Test the Function: With the low beams on, activate the front fog light switch. Observe if another, yellower, and more scattered light source within the same headlight unit turns on.

• Replacement Rule: Must be replaced with a bulb of the same base (PGJ23T-1) and type (H15). Incorrect installation will cause fog light failure or incorrect beam pattern.

Summary: The H15 (PGJ23T-1) is a classic dual-function integrated bulb. Its core value lies in providing owners of many early to mid-period vehicles with a precise OEM-specification replacement part, ensuring the perfect restoration of two critical safety functions: the low beam and the front fog lamp.