Used to program the Original ECT and ECT-2 modules using a PC Serial Port and communication software. Programming is only needed if the standard ECT module programming is not a good match for your car or if you just want to change the way your temperature gauge is operating. Detailed programming and troubleshooting documents are available in the Manuals tab for your specific ECT module.
Serial ports and communications software (Hyperterminal) were standard on Windows XP systems but you can buy inexpensive USB-to-serial adapters for newer computers. You can find free communications software on the Internet by doing a search for "Hyperterminal replacement" or "free serial communications software". The software does not need fancy protocol analyzer features, it just needs to be able to send a plain text file out the serial port.