Current development in the field of trailer operation for automobiles

Buying a new car or pickup truck with the option of configuring a trailer hitch or fitting one to your existing vehicle is becoming increasingly popular. After all, a trailer has a high practical value, as it can be used to transport furniture, large DIY items and bulky waste. Increasing use for leisure activities also helps to give this useful feature a new appeal. The trailer and caravan industry is breaking its own sales records and a bicycle carrier on the trailer hitch is an added benefit for those who like to spend their leisure time cycling.

Trailer connectors: The state of the art

In the automobile sector, the 13-pin trailer connector in accordance with the international standard ISO 11446 has become established with all German car manufacturers. This trailer connector is mainly sold under the name “JAEGER connector”. One of the reasons for this is that in the 1980s, ERICH JAEGER recognized that the old 7-pin connector was inadequate, especially when towing a caravan, and worked with vehicle manufacturers to develop it further. The result was a 13-pin system that was soon standardized and, as an international standard, quickly spread through the market and became widely used. However, an adapter between the two systems is available.

In addition to connecting all lighting signals for trailer lighting, the socket also provides two independent power supply circuits for the trailer, to operate a refrigerator for example.

New possibilities for trailer operation: Solutions of the vehicle manufacturers

Some vehicle manufacturers have recognized this trend towards trailer equipment and offer their customers new functions to increase convenience and safety - e.g. trailer stabilization programs that reduce swaying movements of the automobile-trailer combination and thus increase driving safety.

The rear view cameras in the automobile contribute add to the convenience. In conjunction with a zoom on the trailer hitch, the on-board screen displays the hitch including a docking line dependent on the steering angle. This makes it easier for the driver to see the trailer with the trailer coupling.

A further benefit in terms of convenience is offered by trailer assistants, which make it easier for the driver to maneuver and reverse using a joystick. This also means that drivers who rarely have to steer a trailer do not have to go through the complex rethinking process involved in reversing with a trailer.

The next step: The trailer socket for video transmission

How can safety and convenience be taken further? Car manufacturers have exhausted all conceivable possibilities in vehicle development without direct communication with the trailer. Further development is only possible if the trailer is equipped with peripheral devices and smart applications. However, this requires secure data communication between the towing vehicle and trailer.

ERICH JAEGER develops the SAE J3008 standard together with vehicle manufacturers

ERICH JAEGER was one of the first companies to pursue this idea consistently. In cooperation with an American automobile manufacturer, the automotive supplier set about the technical implementation and development of a new connector - initially for the American market. The result of the cooperation was a new trailer socket and plug, which was raised to SAE standard J3008 (05-2017) and tested according to USCAR-2. Since then, it has been widely used in the USA.

The reason for the initial concentration on the USA is that the general conditions here are different from those in Europe, for example: As in Europe, a connector system for the lighting functions already exists in the USA. In contrast to Europe, however, rear view cameras have been made mandatory for new vehicles in the USA to allow a view behind the vehicle when reversing. In a country where trailers are larger and heavier than on European roads, it is therefore logical to offer the driver a safe view behind the entire vehicle and trailer combination.

 Pin no.Function
2CAN + H
3CAN - L
4PSI5 + Sensor (Peripheral Sensor Interface)
5PSI5 - Sensor (Peripheral Sensor Interface)
8Video Ground/Shield
9Video +
10Video -

New functions, new products

When developing the connector, the initial focus was on video transmission of what is happening behind the trailer. In the course of the standardization work, however, the need to integrate further technologies for open wire communication between vehicle and trailer also emerged; this should anticipate possible future functions:

The new connector provides three pins for simple analog video transmission. If a camera is installed on the trailer, it enables the driver to see inside the trailer, when transporting horses for example, or what is happening behind the trailer.

For contact pins 2 and 3 of the new connector, ERICH JAEGER specified the CAN data bus signals CAN-H and CAN-L. This enables communication between vehicle and trailer via protocol J1939 with a data rate of 250Kbit/s.

As a result, the following functions are possible:

  • Tire condition monitoring
  • Tire pressure
  • Brake wear
  • Light signals

Another safe interface in the new trailer socket is the integrated PSI5 interface (PSI5=Peripheral Sensor Interface 5) integrated in pin 4 and pin 5. Originally developed for safe communication in airbag systems, the sensors can communicate with an ECU (Electronic Control Unit) via two twisted cables at up to 189 kbit/s.  
This interface enables integration of further sensors for driver assistance systems - for example for autonomous driving.

New independent trailer socket developed by ERICH JAEGER

After the successful market launch of the new trailer socket in the USA, ERICH JAEGER has added the socket to its product range for further applications - including in Europe. While in the USA the 12-pin socket was only available in combination with the 7-pin connector according to SAE J2863, the company’s engineers have now developed a 12-pin single version for transferring the video signal. This version also meets the demanding requirements of USCAR in terms of water resistance. A waterproof connection plug is also available within the wiring of the vehicle electrical system.

Technical specifications

  • 12A/channel at 12V nominal voltage
  • Extremely robust and reliable in very harsh operating environments from -40°C to +85°C
  • Highest requirements for water resistance (IPX9K, IPX7)
  • High number of connection cycles over the entire life cycle guarantees a long service life for the socket
  • Simple plug and play (straight plug direction)
  • Sealed rear plug connection for cable or wiring harness connection

Special features of the European automobile industry

With the new trailer connector according to SAE J3008, the US vehicle industry has taken the lead in terms of new functional features to increase safety and convenience.

Often German or European solutions cannot be transferred to the US economic area and vice versa.

But the objectives are identical:

  • integration into a system that also meets the highest safety requirements of automated driving functions with a safety level according to ASIL (Automotive Safety Integrity Level)
  • Reverse compatibility

An independent technical solution and implementation in Europe is possible by means of a new plug connection. However, there is a risk that a second connector in addition to the 13-pin standard “Jaeger connector system” may not be accepted by users. A second trailer socket naturally also requires additional installation space. This may pose a problem for some car manufacturers. It is therefore unlikely that a connector that is not compatible with the current connection patterns will be launched on the market soon. In order to increase acceptance and accelerate a market launch, attention should therefore be paid to compatibility with older automobiles and trailers.

Solutions for new trailer connectors

Technologically, a hybrid connector meets the requirements for a compatible and easy-to-use trailer socket for video transmission. The procedure here is to integrate a new Ethernet interface according to the Automotive Ethernet Standard 1000BASE-T1 into conventional contact systems.

With the new trailer connector according to SAE J3008, Erich Jaeger meets all of the requirements of connectors for the American automobile market in the future. Use in Europe would also be possible immediately, but may encounter obstacles.

ERICH JAEGER is happy to present its concepts and solutions for a new, purely European solution.