What is J2534 protocol connector to cars?


J2534 is a computer-to-vehicle connection standard. Because the US government requires all car manufacturers must provide this standard for programming (Reflash) emissions-related control boxes. That means you don’t have to be a mechanic, a technician.

You can be a car owner or just a casual car enthusiast. As long as you own a J2534 (J2534 Pass-Thru device) plus a little software knowledge, you can program the ECU control box. In some cases, you can even diagnose the car with full features like using the company’s specialized equipment.

What is J2534 Device?

The J2534 device is hardware that helps to communicate between the computer and the vehicle. Its responsibility is to receive, transmit and translate information reciprocal between the computer and the ECU into a J2534 standard protocol, which both the ECU and the computer (specifically the software) understand.


Why was J2534 formed?

History of j2534 device

Since OBDII was born in 1996 and is now gradually expanding to hybrid and electric vehicles. Electronic control systems on vehicles have developed dizzily. There are many control boxes on vehicles. Most people think that only mechanical parts or electrical and electronic parts are easily damaged and repaired. However, the software in the control box on the car needs the most repair. And updating the software is the only way to fix some problems like:

  •  Improve vehicle performance
  • Increase power and reduce fuel consumption
  • When some error code appears, the only way to fix it is to update the software
  • In addition, The control box’s software updating also helps the mechanical parts work more smoothly, helps to increase the durability of the details in the system (the image below is the software update process of the ECU control box on Kia Carnival cars). 

According to SAE’s research data, if there are ten vehicles on the road, 7 out of 10 vehicles need to update the control box software.

However, the electronic control box software updating is only done by the manufacturing’s specialized devices of the or high-end appliances. These devices are inevitably costly, and each manufacturing must have its own device. It is impossible things for garages that want to repair cars. Think of a garage that many different car manufacturers have to maintain and repair, but each company has to invest in a separate device. How can the garage meet it?

Therefore, the American Society of Automotive Engineers SAE has proposed and supported by environmental protection organizations such as the EPA (Environmental Protection Agency) and CARB (California Air Resources Board). According to government promulgation, J2534 has become a standard mandatory requirement for all vehicles manufactured since 2004 in the US. 

J2534 Characteristics

J2534 passthru supports the following connection protocols: ISO9141, ISO14230 (KWP2000), J1850, CAN (ISO11898), ISO15765, SAE J2610, J1939 (since 2005). Consequently, J2534 supports most of today’s connection protocols. About the connection between the computer and the vehicle: J2534 can be connected by RS232, USB, or via Bluetooth, Wifi…

Typically, a J2534 device will have the shape of an OBD II jack. If the vehicle diagnostic jack does not obey OBD II standard, we must know what information about each pin on the diagnostic jack is to extract the connection wire manually.

The maximum length of the J2534 device is 5 meters. If it is longer, it will not guarantee data transmission. The J2534 device requires sufficient 4Kb buffer memory in transmitting and receiving data. And the processor chip must be fast enough to process all the information without being missed.

You can understand this: Any device that is not a diagnostic device provided by the manufacturer, but it can diagnostics for that manufacturer’s vehicle, can be considered a J2534 device.

Some J2534 devices: Scanmaster, Mongoose, VCM II, Open Port, VAS5054a. There are also many other j2534 cable available on the market today.


Some famous passthru device manufacturers such as Xhorse, VXDIAG, DG Technologies, DrewTech, etc. But perhaps the most common is DrewTech’s Mongoose device. There’s a Mongoose Pro cable that I bought from OBD in my garage. If you’re interested, you can refer to it. Especially for those who just opened the garage, I recommend OBD because there’s much support.

Why should a garage need a j2534 pass thru device?

As a garage, you definitely need a j2534 passthru device for the following reasons:

  • First, if you have just opened a garage, you probably don’t have much money to buy each manufacturing’s diagnostic machine. Meanwhile, if you use J2534, you only need one device that can be used on multiple vehicles. For example, a Mongoose device can be used on Toyota, Honda, and GM software
  • Increase profits by providing services that previously had to be done by the manufacturing. You can program the ECU control box on the car, the thing that looks pretty sublime but turns out to be very easy if you know how to do it. I will share with you how to program the control boxes on the car in the following article.
  • Overcoming the above vehicle problems, the J2534 device is not just for programming the control box, but in some cases, you can diagnose the vehicle with full functionality, such as using a specialized manufacturing device.
  • Provide the services necessary to keep your feet and expand your customers. In fact, the software update for the ECM of the vehicle is not the main service of your garage, as it is not much profitable. It is only a supplementary service to increase customer satisfaction and increase the reputation of your garage.

In addition to the J2534 protocol, there is another protocol that is also used by many technicians today, which is DOIP. 

For more information about diagnostics as well as vehicle-related software, Please contact directly via WhatsApp: +13155472355. We have a lot of documentary files on car repair that may help you.


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