I've gone through the electrical section on how to interpret the various symbols but could not find the explanation for this one: a wire that points to a rectangular box with a number inside it. Where does this wire go? What does the box and number inside it means?
For example: Section 15, p 218, track 60 is the water separator sender. pin 2 of the sender has a wire that ends in a box with "18" in it. Where does this wire go?