{"id":2547,"date":"2016-12-21T12:34:21","date_gmt":"2016-12-21T12:34:21","guid":{"rendered":"http:\/\/tomdenton.org\/blog\/?p=2547"},"modified":"2016-12-21T12:34:21","modified_gmt":"2016-12-21T12:34:21","slug":"introduction-to-sae-j2534-pass-through","status":"publish","type":"post","link":"http:\/\/tomdenton.org\/blog\/?p=2547","title":{"rendered":"Introduction to SAE J2534 (Pass through)"},"content":{"rendered":"

Introduction<\/em><\/strong><\/h3>\n

J2534 is a concept that enables flash programming of an emission related ECU regardless of the communication protocol that is used by the ECU. The purpose is that only one tool (hardware device), often referred to as the pass-thru device, should be needed for all kind of ECUs. The connection between the J2534 device and the ECU is a SAE J1962 connector. The J2534 hardware device is to be connected to a standard PC which holds the Application Program Interface (API) from the vehicle manufacturer (Figure 1). The connection between the PC and the J2534 hardware device is up to the manufacturer of the tool, but USB is probably the most common. A J2534 API DLL is provided from the hardware tool developer which handles the communication to the PC. The J2534 document withholds requirements for the hardware and software of a J2534 tool. The communication protocols supported are; ISO9141, ISO14230 (KWP2000), J1850, CAN (ISO11898), ISO15765 and SAE J2610. In 2005 J1939 was also included.<\/p>\n

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Figure 1. J2534 setup.<\/p>\n

Background<\/em><\/strong><\/h4>\n

Vehicles become more and more complex and almost every function is controlled by an Electronic Control Unit (ECU). The ECUs are often connected onto a communication bus to be able to share data between each other. The most common protocol is CAN, but there are other protocols. There are many Vehicle manufactures and almost as many different communication protocols. Every vehicle manufacturer has a tool for analyzing and reprogramming their product, and this tool is often expensive. This makes it difficult for a car, bus or truck workshop to analyze and repair all kind of vehicles.<\/p>\n

U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (ARB) have been trying to get vehicle manufactures to support common emission-related services for the aftermarket. The Society of Automotive Engineers (SAE) created the J2534 standard, in 2002, to promote the EPA and ARB in their work.<\/p>\n

Hardware Requirements<\/em><\/strong><\/h4>\n

The J2534 hardware works like a gateway between the vehicle ECU and the PC. This pass-thru device translates messages sent from the PC into messages of the protocol being used in the vehicle ECU. J2534 supports the following protocols:<\/p>\n