Almost every running heavy duty vehicle with gross vehicle weight over 7.5t has a trailer connected. For fleet managers it is important to know trailer specific information like gross vehicle weight, axle weight, brake status, tire pressure, ABS activation, roll-prevention activation, door statuses and EBS braking related information.
In this section you can read about tractor-trailer communication protocols, and get basic information about the EBS braking systems.
The ISO 11992 based motor-vehicle and trailer connection is often just referred as the Trailer CAN communication. It is different from the ISO11898 in 3 ways: 1. the voltage levels of ISO11992 are 24V, the topology can only be point-to-point connection, and the ISO11992 has also a single wire operating mode, enabling to maintain full communication between towing and towed vehicle also in case of a wire problem.
EBS – Electronic Brake System
EBS (Electronic Brake System) is a new generation of commercial vehicle braking systems. Since 1996 it contains several functions like ABS, ASR, CFC and VDC integrated into one system. The braking is controlled electronically to get shorter response time and braking distance. The pneumatic control is only supported in backup mode to have redundancy in braking control (and for backward compatibility).
EBS has many extra functions over the pneumatic systems, such as optimum braking force distribution (also between tractor and trailer), yaw control and roll over prevention for safe grip on the road, brake pad wear control, tire management, trailer weight calculations, and many others.
EBS systems core components are EBS modules located in the motor vehicle and in the trailer (TEBS module), changing information via the ISO 11992 (Trailer CAN) bus.
TEBS – Trailer Electronic Brake System
Trailer Electronic(ally Controlled) Brake System (TEBS) is a high-level brake control system for vehicle combinations. The trailer EBS module is controlled by the motor vehicle EBS module via ISO 11992 (Trailer CAN) bus and collects information about the vehicle state (speed, acceleration and other braking related parameters) to perform optimum braking of the vehicle combination. Other sensors are directly connected to TEBS module such as tire pressure, temperature sensors, axle weight information, etc.