Problem starting gu patrol zd30

I have my 2003 gu patrol running the 3litre zd30. I have owned the car for about a year now occasionally about once a week the engine light and glow plug light flicker on my dash and don't allow me to start the car. It's like the battery cable is loose or something however there is still power from the battery as the starter motor still works and turns the car over it just won't start like an immobileser is on or something any ideas of what it could be ? It can some times take 10 minutes of this light flickering before the car will start

Possible a faulty ECU relay or the main ECU earths on RHS of the engine are loose or corroded.

I pulled off all earth straps at the motor and battery and gave them a good clean back to fresh metal and let system reset it self by leaving it off for a while then put back on and haven't had an issue thanks for reply Yendor