Assistance w/ Engine Code description

My Check Engine line came on and started flashing. I when to get it checked out and the code that it gave me was P1399. The describion for that code is Glow plug circuit, High side, High input. I dont understand what that means. Can anyone clearify that some more. And the problem with the car is that my car is smoking really bad, white smoke sometimes a bit greyish. Thanks for the help.

misfire.

check spark and fuel.