Hi Nuna

Does the truck use the Jungnheinrich 616k controller which is the dual unit which incorporates the Pump controller and traction in one? If so remove the black plastic cover from the top pf the card and if you look just underneath the card near the connector ends there should be 2 leds on either side, one for the pump circuit and one for the traction. You can get fault indication off this green lit leds indicate its ok unless a fault occurs you get a flashing red led very small but easily visible when lit.

I had a similar problem on an etv214 older version but used this controller. When i removed the cover i noticed the leds were not lighting up which indicated that there was a feed missing , feeds were ok and it was down to a card problem in the end.

If you leds are not lighting up check the key supply to the card input.

On the other hand if it uses the AS4814 controller it also has LED's on the top card from what i understand, might be worth looking to see if they give any fault indicators.