Here are some technical details.
At the front there is the ultrasonic sensor which measures the distance, and if the truck is to close to an object, which is 10 cm in this case, the NXT will warn the driver.
The motor inside the cabin makes the truck steer.
At the back of the trailer there is some sort of suspension for the wheels.
As I have told, there were some errors with the bluetooth communication.
Here are the programs needed to use the truck, so you might be able to solve my problem..