I tested the ground on the circuit board while the cluster is fully connected and can see good ground, since all other functions of the cluster work fine (lamps for headlight, direction lights, the whole signals when turning the key to position 2 etc..) except the needles.
If I leave the car for some hours then the first time I start the engine, the needles come to life then dead again at the next trial (turn engine off and restart) without me touching anything, the game can be repeated after several hours again and again.
I reached behind the cluster, wiggled the harnesses to see if there is anything loose with no success.
I make sure that the plugs connected to the cluster are firmly inserted; same situation.
Someone suggested that the relay unit K40 could be the cause. Mr Dalton, do you share that opinion? Is the K40 positively linked to this defect? If yes I can buy a new one.
Thanks for being patient with me.