Why my FVDI K-LINE doesn't work?

My FVDI can't build connection with any K-LINE car.

Its hardware must have problem.

How to solve it.

Below solution possible can help you:

change this two chips: L9637D and ADG1406BRUZ  

If K-Line still not work, please do the below:

replace K6 Omron 61g1 MOS relay with an original working one.