Collection: Sockets & Lamp Holders

Bulb Socket: The Unsung Cause of a Light That Won't Turn On

When a taillight or turn signal doesn't work despite a new bulb, the immediate reflex is to suspect the bulb. However, the real cause is very often the socket — the part that receives the bulb base and transmits current via its contacts.

Typical symptoms of a faulty socket:

• Corroded contacts due to humidity — poor electrical conductivity
• Melted plastic due to the heat from an overly powerful bulb
• Broken or bent pin — intermittent contact
• Green corrosion from water infiltration (typical for clearance or license plate lights)

Simple multimeter diagnostic: measure the voltage at the socket input (wiring harness side). If voltage is present but the bulb doesn't light up, the problem is in the socket — it needs to be replaced.

Replace Your Socket Rather Than Your Light Assembly

A replacement light assembly can cost between €150 and €800 depending on the vehicle. A replacement socket costs a few euros and solves the problem in the vast majority of cases. Simple procedure:

1. Remove the old socket from the light housing (unclip or quarter-turn rotation depending on the model)
2. Cut the wiring 5 cm from the old socket
3. Connect the wires to the new socket (crimp connector or solder + heat shrink tubing)
4. Clip the new socket back into the housing and test

Essential for older vehicles where original sockets have endured decades of humidity and heat — replacing them is often the solution for finicky lights that resist all other repairs.

Identify Your Socket — by the Bulb Base

Each socket corresponds to a specific bulb base type. To order the correct part, note the base inscribed on the bulb from your faulty light: BA15S socket for single-contact bayonet bulbs, BAY15D socket for double-contact, W5W (T10) socket for capless wedge bulbs, etc.