[petdr]

Here are some suggestions:

Sounds like you need to work on the leadership issue.
Remember you are the leader so you need to reinforce the basic commands again if the dog is not listening. When you call your dog he MUST come. He MUST sit. He needs to relearn these commands. Make the rewards unbelievable for your dog and he should learn them. So when the truck comes divert the dog's attention through tasks and rewards.

Let the people in the truck give the dog rewards upon their arrival so the dog may learn that the truck means rewards.

Reward the ABSENCE of barking with praise and other good stuff.

Definately get a leash length that prevents him from peeing or reaching the truck. The peeing doesn't seem to be important, it is the result of the behavioural conflict.

Hope that helps

Julie Sansregret - AHT, Dog trainer
Guides Canins
1313, rue PineRidge,
St-Lazare-de-Vaudreuil, Qué.
J7T 2M7 (450) 424-1469
www.guidescanins.com