Error code P0620 causing multiple problems WG CRD 2003

[JimboJones]

Hi All,
I have a 2003 GC 2.7 CRD Overland with 244ks
Bought the car with 227ks on it. I did about 15000ks of trouble free driving until one day the engine light came on then the car went into limp mode seconds later.
I had the car scanned and the error code P0620 says there is an open or short circuit somewhere in the generator control circuit.
I have load tested the Alternator and battery (myself and auto elec.) and they are fine.
I swapped out the ECU for a different one and it still had the same problem(replaced again with original ECU).
I fitted a voltmeter directly to the battery whilst driving and there is no voltage drop when the engine light comes on and car goes into limp mode.
The other codes are 520, 235, 651, 530, 2120. They are all a flow on effect of the open or short circuit from the generator control circuit. 2120 (TPS malfunction) puts the car into limp mode.
So at the moment I am trying to find all the EARTH straps. Does any know where all the engine earth straps are?
Also even though the alternator tests ok could that still possibly have an open circuit internally causing code P0620 ?
Thankyou in advance for any advice.

[5oclock]

Jimbo, have a look at Drovers Sticky thread, there is a link on post6 for workshop manual, wiring will detail all earths.I do know very important earth connection is on passenger mud guard and i have read that if this one is disconnected while the engine is running it can destroy the ECU.Manual also details codes for 2.7CRD which are different to petrol engines.

[JimboJones]

Cheers 5oclock, I'll look into it.