How do I identify J1939 ?

The Controller Area Network (CAN) protocol is widely used in vehicles for reliable and efficient communication between electronic control units (ECUs). However, with the emergence of the Society of Automotive Engineers (SAE) standard J1939, a protocol for in-vehicle networks, the need to identify J1939 has increased. In this article, we will discuss the differences between ISO 15765 and J1939, as well as several methods to identify J1939 in a professional manner.

ISO 15765 and J1939 Differences

ISO 15765 is a standard developed by the International Organization for Standardization (ISO) that defines the diagnostic communication over the CAN protocol. It specifies the requirements for a network layer protocol to address the needs of diagnostic systems communicating on a CAN bus. ISO 15765 provides a framework for reliable, secure, and efficient communication between ECUs in vehicles.

On the other hand, J1939 is a standard developed by the Society of Automotive Engineers (SAE) specifically for heavy-duty commercial vehicles. It defines the communication protocol used for in-vehicle networks, such as trucks and buses. J1939 is based on the CAN protocol and is designed to support the reliable exchange of information between various ECUs in a vehicle.

Identifying J1939

Identifying J1939 involves understanding its structure and elements. J1939 uses a two-wire CAN bus system for communication, with data transmitted in the form of messages. These messages contain important information such as engine speed, vehicle speed, diagnostic trouble codes, and more.

To identify J1939, one needs to be familiar with the unique identifiers and parameter groups used by this protocol. There are several ways to identify J1939 in a professional manner:

Physical Inspection: Start by inspecting the vehicle's hardware components. Look for connectors labeled with "J1939" or "CAN." These connectors are typically found near the engine or inside the cab. Additionally, locate the diagnostic connector, often referred to as the "J1939 connector," which is used to connect diagnostic tools.

Using diagnostic tools: Download and install a diagnostic tool such as Scantool or AutoConnect. These tools allow you to read the data from the J1939 protocol and identify any issues or concerns.

Checking the vehicle's documentation: Review the vehicle's documentation to understand the J1939 protocol and its requirements. This may include the vehicle's wiring diagram, diagnostic diagrams, and technical specifications.

Testing with a vehicle simulator: Use a vehicle simulator to test the J1939 protocol under different conditions. This can help you identify any issues or limitations with the protocol and ensure it meets the requirements for your vehicle.

Conclusion

In conclusion, identifying J1939 requires understanding its structure and elements. By familiarizing yourself with the unique identifiers and parameter groups used by the protocol, as well as using diagnostic tools and testing with a vehicle simulator, you can accurately identify J1939 in a professional manner.