C2 indicator lamp

According to the statutory requirements in some countries concerning the monitoring of the trailer flashing lights, the C2 indicator lamp indicates to the driver whether the trailer flashing lights are functioning. It has to be installed within the driver’s field of vision or, in some cases, is already present in the dashboard. Some vehicle types already have a slot intended for the C2 indicator lamp in the combination instrument. If so, merely an adequate lamp has to be retrofitted. The activation of the indicator lamp is carried out by the flasher unit with C2 output.


Prior to the introduction of the “Jaegertronic”, the C2 indicator lamp was used in every wiring harness. Unless there is a standard C2 indicator lamp in the vehicle, we recommend an installation of the “Jaegertronic” to avoid interference with the combination instrument.

CAN data bus

In modern vehicle type series, the CAN (Controller Area Network) data bus interlinks the different control devices. The control devices communicate via messages or wires. For example, information concerning engine speed, accelerator pedal and engine control are transferred digitally by a bus system. In some vehicles, the states of the lighting functions (e.g. brake light, rear light, flasher) such as ON, OFF or ERROR are likewise digitally transferred by the CAN bus.


Due to the increasing complexity, the installation of universal wiring harness kits into vehicles with CAN data bus is merely possible as an exception. We recommend the installation of a vehicle-specific kit.

Charging line

A charging line can be established via contact number 10 of the 13-pin connector according to ISO 11446. This contact is primarily used to charge a battery in the trailer (for example to supply appliances in a caravan).

The charging line is connected to the battery via a cut-off relay as soon as the ignition is started or the engine is running.

The connecting cable to contact number 10 and the respective common return lead to contact number 11 should have a diameter of 2.5 mm2 and a fuse protection of 20 A at most.


According to the ISO 11446 standard, the common return contacts number 3, 11, and 13 must not be connected electrically conductive.


The check-control system is part of the vehicle electronics and, when ignition is started and while driving, monitors several vehicle functions such as the lighting functions (parking light, dipped beam, full beam, brake light, license plate lighting, reverse light, and rear fog light).

A failure of the lighting is indicated in the dashboard by light symbols, acoustic signals or in the multifunctional display of the car computer (partly in plaintext).

As there are vehicle types with as well as without check-control, we offer wiring harness extension kits in our wiring harness product range. These can be used as an upgrade to the basic wiring harness kit (7-pin or 13-pin). The check-control extension kits ensure a high-resistance and lossless tapping of the check-control functionality in the vehicle. Besides, the functionality is connected to the trailer by a steady plus supply (clamp 30).

Crimp technology

In the manufacture of wiring harnesses, ERICH JAEGER applies amongst other things the crimp technology for a solderless electrical connection. In the crimping process, a connector (crimp contact) and a conductor (strand) are compressed to a tight connection by mechanical compression. In this way, a gastight compression of wire and contact plug is created. By applying the crimp technology, a reduced contact resistance and a close connection of the contacts can be guaranteed.

ERICH JAEGER has introduced a group-wide crimping standard that even exceeds the requirements of the valid industrial standard DIN 46249. Therefore, high-quality crimp connections can be guaranteed at any time. A good degree of compression is characterized by a completely filled crimp barrel in which the strands in the wire crimp area are completely compressed in a honeycomb structure (see picture). The microsections are regularly checked for such a compression and still other parameters in modern cross section laboratories