And there really isn't a pigtail indicator.

are you sure ?
even new diesels need thier plugs warmed first (and have a pigtail
light) ....

Modern diesels often run the pump and glowplugs to "prime" the engine when
you unlock the doors, so there is no need for a light. It also means that
starting can sometimes be slightly more difficult if you wait too long
before starting the engine.

It is also why, on a modern diesel, if you accidentally fill with petrol, do
ABSOLUTELY NOTHING until the fuel can be pumped out. DO NOT touch the keys
or attempt to lock or unlock the doors. Otherwise, you can find your petrol
has caused several thousand pounds worth of damage to the fuel pump.

Christian.