13-pin plug

The 13-pin plug (ISO 11446) is the European standard electrical connector between tow vehicle and trailer, replacing the older 7-pin N + S sockets since 2008. It carries lighting, side-light and fog-light signals, the trailer leisure-battery charge feed, and a line for a rear-view camera.

Pins 1–7 follow 7-pin N, so a 13→7 adapter restores backward compatibility. Extra-contact assignments: pin 9 — permanent +12 V (interior lights, central locks) with pin 13 as its ground; pin 10 — ignition-switched +12 V (charges the trailer leisure battery and powers the fridge while driving) with pin 11 as its ground; pin 12 — reserved, often used as a reversing-camera trigger signal. Separate earths on pins 11/13 matter for diagnostics: "no charge while driving" → check pin 10/11; "no interior light when parked" → check pin 9/13. The cable assembly is standardised; common brands include Jaeger (PRO/ECO) and Westfalia. In the UK, 7-pin N + S sockets are still in widespread parallel use, while the continent has fully switched over.