What is J1939 protocol, and why should you care?

When looking at different engines, you may encounter the term J1939, and this term is important, but why?

J1939 is the proprietary name of the protocol used by engine manufacturers for vehicles. Much like spoken languages, such as Chinese or English, J1939 Protocol refers to the language that the engine “speaks”. The ECU of the engine takes the signals sent by the engine sensors and either makes adjustments (as in fuel to air mixture) or communicates that information, either to a display, or to a software program.

Much like language in humans requires listening and speaking, an engine protocol requires both receiving information and communicating that information. So, what is J1939. J1939 is the SAE standard that engine manufacturers typically use to ensure that the engine is in compliance with industry standards. Since the majority of marine engines are derived from automobile, truck, or other engines, this protocol is largely standard. Additionally, there are various ISO standards that are also required, often mandated by law. However, J1939 is not mandated. It has simply become the overall standard that most engine makers use.

Why is this? In short, nothing legally requires an engine maker to use the J1939 protocol, but should an engine maker not use J1939, they would face major problems with component compatibility (like ECUs), monitoring systems, and even from manufacturers of gauges. Additionally, since the maintenance shops at marinas, government, and commercial operators are equipped to deal with J1939, end user maintenance becomes much easier and cheaper when standards are in place. Does Marinediesel comply?

Like most manufacturers, Marinediesel uses J1939 in the programming on our ECU. J1939 is an incredibly flexible protocol, and there are differences between J1939 for off road and on road use. However, most engine monitoring systems should be able to communicate with our engines, not only with fault codes, but in monitoring performance. Additionally, aftermarket vessel systems that require engine data (such as fuel management systems) should be compatible with Marinediesel engines.