Disclaimer: This article is for educational purposes. SAE J1939-73 is a copyrighted standard. Always purchase official copies from SAE International. The author is not affiliated with SAE.
You can acquire the standard by visiting the SAE International J1939-73 Product Page .
SAE J1939-73 is a part of the SAE J1939 protocol, which is a standardized protocol for vehicle networks. The protocol was developed by the Society of Automotive Engineers (SAE) to ensure interoperability and compatibility between different ECUs from various manufacturers. SAE J1939-73 specifically focuses on the application layer and transport layer of the protocol, defining the rules for data communication, message prioritization, and network management.
To decode the diagnostic information broadcasted on the CAN bus, you must understand how J1939 handles faults: Sae J1939-73 Pdf
A newer global standard intended to unify diagnostics across light- and heavy-duty vehicles. It is based on the UDS protocol (ISO 14229) , which is a powerful request/response system. It can run over multiple underlying transport layers, including CAN (ISO 15765) and other networks. This is a more complex, modern standard designed for future vehicles, but J1939-73 remains the established legacy standard for heavy-duty vehicles currently on the road.
SAE J1939-73 is the backbone of vehicle diagnostics in the heavy-duty industry. By standardizing how faults are reported, cleared, and displayed, it allows a single diagnostic tool to service a diverse fleet of vehicles. For embedded engineers, the standard eliminates the ambiguity of error reporting, while for technicians, it provides a consistent interface for troubleshooting complex machinery.
For those interested in learning more about SAE J1939-73, the SAE J1939-73 PDF document can be downloaded from various online sources, including the SAE International website. Additionally, several software tools and libraries are available that provide SAE J1939-73 protocol support, enabling developers to design and test SAE J1939-73 compliant systems. Disclaimer: This article is for educational purposes
The standard defines a series of specific message identifiers used for diagnostic sessions. These are critical for aftermarket tool development and include:
Beyond reading basic trouble codes, the SAE J1939-73 PDF outlines complex diagnostic procedures used for programming and deep troubleshooting:
DM2 functions as the vehicle's historical log. It contains a list of faults that occurred in the past but are not currently triggering a failure. Technicians check DM2 messages to identify intermittent electrical shorts or recurring component degradation. DM3: Diagnostic Data Clear/Reset (PGN 65228) The author is not affiliated with SAE
The J1939-73 specification establishes a series of standard Diagnostic Messages, numbered sequentially from DM1 to DM52 (and beyond in newer revisions). The most frequently utilized messages include: DM1: Active Diagnostic Trouble Codes (PGN 65226)
The SAE J1939-73 protocol is a widely used standard in the automotive industry, particularly in the realm of heavy-duty vehicles, such as trucks, buses, and construction equipment. This protocol is a part of the SAE J1939 protocol suite, which is a set of standards for communication between electronic control units (ECUs) in vehicle networks. In this article, we will delve into the details of SAE J1939-73, its applications, and provide an overview of the protocol's specifications, which can be found in the SAE J1939-73 PDF document.