First problem I have a stock 2004 tahoe, hptuners pro, and a RCA cambio 10.1 windows10 home OS 32bit. I can't read the ecm in fast mode and give a x7f fail with a download timeout but if i cycle the key a few times it will read in slow mode but that tales 30 minutes just to pull the file. Write time is normal. I've updated everything on the OS I can use scanner like normal on both vehicles. I also have tried my old laptop with the same issue it was a. HP runing windows 10 pro 64 bit.
The ECM problem is a when using a homemade bench tunning tool my 2002 2wd suburban ecm will read in fast mode and scan but will give me a x7f fail code when writing.
Please help and thanks in advance