If the light for the glowplugs doesn't come on, I would eyeball the glowplug relay.
Twice in the last 9 months my light did not want to come on, the first time (somewhat out of frustration
) I gave the relay box a little "love-tap"...this motivated it enought to get things glowing again.
I imagine my relay is getting a little old, but I'll wait till it gives up the ghost before I replace it.
Might be worth checking out in your case.