I have a 1992 chevy 6.2L deisel.
The glow plug light is not coming on there for it will not start?

Have you changed the glow plugs out at all? Or is it just the light?

Check your glow plug relay switch.Its a grey box located near the back of the engine with a black plug in.This is what sends the signal to turn on and time the plugs to warm up be4 you start it.This relay costs about 80 bucks in canada.If you never changed your glow plugs it mite be time to do so.Use a amp meter to check for continuity,that will tell you if the plugs are shot,no continuity,plugs are worn.Glow plugs run any where from 6 to 10 bucks a piece.Good luck.