The goal is to walk your Yorkie, with him being on your left (even if that needs to be on the traffic side of the sidewalk) and 100% completely ignore any attempts to run, go behind you, jump, bark or other behavior. With the leash kept exactly at the length required for your dog to be right by your side, with the harness on and walking at the correct pace, you will be able to forge ahead despite any actions your Yorkie tries to take and will be able to do this without harming him.
Be careful to not tense up when you see or hear a car coming. Dogs are remarkable at being able to read and sense an owner's feelings. If you feel nervous in anticipation of how your Yorkshire Terrier is going to react to traffic, this in and of itself can make a dog nervous. As the car is coming closer, reaffirm proper walking by matter-of-factly saying "Heel, good heel" several times in a confident voice.
Do not look over at your Yorkie when the car passes. Simply walk, holding the leash tightly as if nothing at all happened. Once the car if out of sight, if your Yorkie did okay you can pause and offer a small treat (have these ready in your pocket for easy dispensing). If he did indeed jump or try to run, don't offer a treat, however do speak in a casual voice and keep going.
After 20 minutes, it will be time to end the session and whether or not your Yorkie was afraid or did indeed handle himself well, give praise and a treat for a job well done (or for at least trying). It is important to show enthusiasm both before and after a walk; dogs often tend to eventually believe that something is fun if the owner acts as if it is.
If a dog is still so scared of even just one car passing by, you can try another method in which you have exceptional treats ready (something like real bacon, cooked crisp and broken up into pieces). When you know that a car is going to pass by, stop walking, kneel down and be looking right at your Yorkie. Wave the piece of bacon to gain his undivided attention, toss it toward the grass and give the 'Find' command. If your Yorkie is finds the treat and gobbles it up without paying attention to the car, this shows that he is able to remove his focus from the threat and fear of the car. This is a good sign that desensitization will work.
Over time, you can progress to simply getting his attention when traffic comes down the street. The next step from that is to simply be able to say his/her name
. Only once he is successful with this, will it be time to move things up a notch.
Step 3- It may take 2 days to get to this point or it may take 2 months; however do not move up to this next phase until your Yorkshire Terrier has proven that he has learned to handle walking with light traffic without any issues. When a dog is exposed to something enough times… and each of those times the owners is showing by example, actions and words that nothing is scary, a dog will ultimately learn the lesson.
This next step in teaching a Yorkie to not be afraid of cars is to go to an area with moderate traffic. Choose a spot that you estimate will have 10 or so cars passing by within a 20 minute time frame. You will repeat the same actions as you did for Step 1.