Classification of car lamp sockets

Main lamp holder models and corresponding applications.

Plug-in type (wedge/T series): Contacts are parallel and fixed by friction. Mostly used for low-power signal/lighting lamps.

T5/T3.75: Backlight for dashboards, indicator lights in very small spaces.

T10 (W5W/194): Headlights, license plate lights, interior reading lights (most commonly used).

T15 (W16W/192): Rear lights, some turn signals (diameter is slightly larger than T10).

T20 (W21W/7440): Brake lights, headlights, high-mounted brake lights (able to carry large current).

T25/T27: Some commercial vehicles or large-power signal lights in special positions.

Snap-in/locking pin type (H/90xx series): With locking teeth or pins, anti-rotation and anti-loosening, mainly used for front headlights/fog lights.

H1: Single wire single leg, high beam or fog light (P14.5s base).

H3: With wire tail wire, fog light or high beam (PK22s base, commonly used in Japanese/off-road vehicles).

H4: Double wire three legs, combined day and night vision (P43t base, commonly used in motorcycles and older cars).

H7: Single wire two legs, mainstream for near vision lights (PX26d base, common in German cars).

H8/H9/H11: With plastic snap-in base, fog light or near vision (PGJ19 series base, H11 is for fog light/near vision universal).

9004 (HB1)/9007 (HB5): Double wire American standard, combined day and night vision.

9005 (HB3)/9006 (HB4): Single wire American standard, 9005 for high beam/9006 for near vision or fog light.

Socket type and other special types:

Physical size priority: The T series numbers represent the diameter of the lamp head (mm). The spacing and tooth shape of the H/90xx series feet must be completely consistent; otherwise, it cannot be installed or has poor contact.

Power matching: When replacing LEDs, it is necessary to confirm the lamp holder's temperature resistance and circuit load. If the original 55W halogen base is directly replaced with a high-power LED, a decoder or heat dissipation base may need to be added.

Identification method: Remove the old bulb to see the bottom characters; if they are unclear, observe the number of legs (H1 single leg, H4 three legs, H7 double legs with teeth, T10 no legs flat shape) and the base shape (round/elliptical/flat square).

Safety warning: Do not mix models (such as forcibly inserting T10 into T15 base), as it may cause short circuit, overheating, or even burning the wiring harness; for combined day and night vision positions (H4/9007), do not install single-wire bulbs.