L300 2.5D Glowing problems - buzzer sound

[GermanL300]

I've a glow-peroblem with my L300 D2.5, built 1996.

Normally theres a click when you turn the key, the indicator light glows a few seconds (depending on the temperature)
and after a second click and the light is off.

Now you hear a kind of buzzing for a few seconds, seems to come from the right side under the front bench
(the car has left-steering) and the indicator light "glows" only (not as bright as normal)

Seems a relais is switching rapidly on/off.

Glow plugs have been replaced, the small preheat-relais also - but no improvement.
I read about an control unit for pre- and pastglowing - maybe the error ist in there?

Is anybody able to identify the problem/sound and the defect component to replace?

Kind regards from Germany, Dennis

[mriguy]

check the ECU board located in the pillar behind the right hand side...often condensation can cause corrosion on the board and cause a short yo occur on the board and you will sometimes hear the glow plugs clicking on and off when the short happens...usually while driving!! gulp!!!