i have a 1998 Jetta tdii that started acting up. The issue is it sometimes won't start. It will turn over great but won't start. Won't even coast start. I've correlated this issue to happening when you turn the key on the glow plug light doesn't come on and only presents when the glow plug light doesn't come on. If you wait 15 min it usually comes on when you try to start it and is fine. Is there a common thing to check for this?? Thanks.