One thing not to do is put mice poison out because they will eat it and then run as fast as they can up one of your heater ducts and then die. The next time you turn your heater on, it's you that's going to die.
It won't matter, you can tear the whole truck apart and you'll never find the mouse and the stink will remain for a couple of years.
The best thing to do is to get a trap (outside the truck) that way you'll know exactly what is going on with the stupid mouse.
Another way is to do the spinny pop can with peanut butter over a bucket of water. They jump on the can to try and eat the peanut butter, but spin and fall into the drink. Some people think that it's cruel, but a mouse trap is too.
I guess you can catch and train them not to break into your garage. Let us know how that works.
