I am trying to plug into my tec 3 6/12 unit for the first time. Im using an old laptop with a serial port. Im not sure why its not working. The battery is making 11.93 volts with the ignition on. I've checked the bios serial port address versus windows, and they match. Ive tried other com ports on wintec, and #2 gives an error and shuts it down. I have a green light on the tec3 unit. SO thats good at least. Im not sure if the new serial cable is bad or not. I am going to try a different pc with a dynex serial to usb connector today and see if I can connect. Any advice or trouble shooting help is greatly appreciated.