This adapter harness works with all of our BenchForce™ PowerBlock switch assemblies. It is meant to be used with scan, tune, and diagnostic tools that have a J1939 connection. Plug the OBD-II end into the PowerBlock, then use your own tool with the other side. This solution is popular among diesel tuners when they are working with heavy equipment such as heavy duty trucks, construction equipment, etc. Be sure to check out our growing list of diesel programming harnesses.