Codes are "flashed" with the wrench light when you connect a code scan tool,but I believe you can jump two pins in the DTC data connector and flash them that way with out a scan tool...any one know if this is correct,know HYSTER has the same set up on some of their trucks the scan tool(s) are made by Rhinda technologies corp for HYSTER and Yale....they also use this system on marine engines like the 4.3 L v 6 and 4 Cyl. Engines.....