Take the ecu out of the car.

Get your spare loom and put the live and earth direct to the battery and see if you get any lights.

Cuts out the whole car loom and potential problems with immobilisers etc.


Also, are you using a USB to Serial Convertor or has the laptop got a traditional 9 pin serial port as I know of a couple of tuners who have had problems with the USB to Serial Convertors