Engine diagnosis requested - Machine gun clicking noise

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Dear Forum members,

Your combined expertese is requested on the following problem that developed this morning on the way to work. Happened in the following order:

1. Glow plug light started flashing, turbo not working. So the usual cure of on and off cleared the light, but after a couple of hundred metres it came on again. Repeated to similar effect.

2. Left it a bit longer and re-started. Now the Engine Amber light illumintated, glow plug light not on anymore. Turbo working again.

3. Had to get out to open a gate and this is where I heard the noise from the engine bay. A 'machine gun' rattle of 5 reasonable loud clicks, a short pause, then repeat. Noise sounded like a very large relay clicking away rythmically. Noise appeared to emminate from NSF of engine bay.

4. I switched the engine off and it gave out about 10 more clicks (engine had stopped so would seem to be electrical) before stopping.

The last 2 were repeated on the final start. Engine seems to be running fine, Air sus seems fine, cruise control worked (common to stop with an ECU failure, I understand).

There, however, is the limit of my knowledge. Has anyone suffered a similar problem? Please tell me its a cheap fix!

CBA