You need to change the driver log on access parameter to an EVEN number to block any access in to the driver settings.

Its parameter 39 you need to change.

You will need a BT CAN service key or BT Truck Com software to do this.

How are you switching the truck on at the moment as there are several options - If its a key switch then change parameter 39 to 2.

If its the standard factory keypad then change parameter 39 to 4.

IMPORTANT if its keypad truck: A BT CAN key connected to the truck will bypass the keypad / start code - truck will start with just the green button.

Catches lots of people out when there programming / changing pin codes.