Questions related to Glow Plug Module

Hi CEans you could have heard about the “GLOW PLUG MODULE”/”GLOW PLUG CONTROL MODULE” . It’s a device which looks similar to spark plug but GPM is widely used in diesel engines. I had also amused by the term plug which reminds me about the spark plug which helps in SI engines to start the combustion.This stirs the question that what is the purpose of a GPM In diesel engines. I found that it resembles spark plug in structure and working too.It helps the engine start especially in cold starts and works as follows:The current passing through GPM produces heat same as that in a toaster and helps to preheat and good diffusion of fuel. We all know the fact that FORD ECOSPORT used this GPM and ended in chaos.

1)What is the root problem of it and how to overcome it?

2)What is the necessity of GPM in compressively ignited engines?

3)How about its usage in direct injected CI engines and Indirect injected CI engines?