2004 BMW 320 Start up problem with BMW 320D

Electrical problem
2004 BMW 320 Two Wheel Drive Manual 70000 miles

Hi,
I have very strange problem with my car.
Its BMW 320 Turbo Diesel.
Year 2004 4 Door Saloon

When I turn the Key on Temperature gauge shows full (100%) High.
and the Warnning (Triangle Symbol) lights up in Insturment Panel.

If I start to start the car in this state, It fails.
If I turn the key on an doff couple of times, temperature guage goes back to normal state and the Warnning (Triangle Symbol) lights goes off in Insturment Panel
This enables me to start the car.

When engine starts it works fine, there are no miss fires. No problems at all.

This happeneds randomly. Even when I start the car cold in the morning.
I changed car battery so its not car battery.
Radiater is fine.
One my friend (Mechanic) attatched the BMW diagnostic computer to it, and shows its faulty glow plugs.

I will be changing these this weekend, to see if this fixes the problem.

Can you show my on diagram where are glow plugs in BMW 320D 2004. So I can change them. Thanks


Also Any idea what could be causing this problem.