Caterpillar J1708 or J1939
Creation date: 11/14/2021 9:16 PM
Updated: 7/28/2025 1:47 PM
In the early 2000s, Caterpillar used both J1939 and J1708/J1587 interfaces on their engines. The easiest way to determine the configuration of your engine is by examining the back of the 9-pin connector. If the engine is equipped with a J17088/J1587 interface there will be a yellow and gray wire at positions J and H. If there is a J1939 interface present you will find wires at positions F and G.
If the back of the connector can't be accessed, you can typically determine pin presence from the front as well. A good, well lit photograph can aid in determining what pins are present. If you are unsure, please take pictures of the front and rear of your connector and send them to info@yachtdevicesus.com.
CAT caterpillar 9-pin diagnostics conenctor SAE - J1708.jpg
CAT 9-pin diagnostic conenctor - with J1939 - thumb.jpg
Cat9-Pin-FrontOfConnector.png