M: What's the AUX pin for? How do I connect it? The PICkit 2 AUX pin is not used for programming PIC microcontrollers, and should be left unconnected. It is only used when programming some Serial EEPROMs. The Readme file under Help > Readme in PICkit 2 Programmer v2.40 provides serial EEPROM connection information under section 3. "Release notes V2.40.00"