7-PIN type S connector 12V
- Updated:
- By: Kevin van Mierlo
Contents
Definition
The 7-PIN Type S connector is an outdated plug standard that was used in the past alongside the 7-PIN Type N connector. Together, these connectors provided the complete electrical control of caravans and other towed vehicles at a time when functions were not yet combined in one connector .
The 7-PIN Type S connector is no longer used in new builds or modern retrofits. This connector was previously used as a supplement to the 7-PIN Type N connector for additional functions and has been functionally replaced by the 13-PIN connector.
While the Type N connector was used for basic lighting, the Type S connector was used for additional functions, such as:
- reversing lights
- constant power supply
- battery charging while driving
This system was specified in the ISO 3732 standard. In current practice, the Type S connector is no longer used in new builds or modern retrofits. The functions of both Type N and Type S were later combined in the 13-PIN connector (ISO 11446), which has since become the standard. The Type S connector is now found exclusively in older caravans and existing installations.
Wiring diagram 7-PIN connector type S (12 V)
The Type S connector had a different function assignment than the Type N connector, despite both being 7-PIN connectors. This made the connectors not interchangeable.
| PIN | Function | Colour |
|---|---|---|
| 1 | Battery charging current | Grey |
| 2 | Free (optional) | Black |
| 3 | Mass for PIN 1 | White |
| 4 | Free (optional) | Green |
| 5 | Reversing lights | Blue |
| 6 | Mass for PIN 2 (constant current) | White |
| 7 | Constant power supply | Red |
Because the pin assignment differed from that of the N connector, confusion could lead to interference or damage to connected equipment.
When was the 7-PIN type S connector used?
The 7-PIN Type S connector was mainly used in combination with the Type N connector on vehicles and trailers with two separate connections. Common applications included:
- older caravans with refrigerator or battery operation
- Trailers with reversing lights prior to the introduction of the 13-PIN connector
- motorhomes and vintage vehicles with separate power circuits
In newer vehicles and trailers, this system has been almost entirely replaced by the 13-PIN connection.
CAN-bus problems with modern vehicles
When an older trailer with N+S connections is coupled to a CAN-bus vehicle, interference may occur:
- LED lighting does not work or gives error messages
- Constant current supply is not recognised
- Battery does not charge while driving
View our CAN-bus solutions or read the article:
Troubleshooting CAN-bus interference in LED lighting
Frequently asked question
Why have N and S plugs been replaced by 13-PIN connectors?
The dual-connector solution was error-prone and cumbersome. That is why, with the introduction of ISO 11446, a single, safe and waterproof 13-PIN connector with integrated N and S functions was chosen.
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Author
Kevin van Mierlo
Lighting expert at TRALERT® - Kevin tests lighting and finds out everything about legislation. He can tell you all about it.
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