What should you do to warn oncoming traffic in the event of a vehicle breakdown?

• Use portable warning devices and turn on your emergency warning lights.
  Explanation:

  "Portable warning devices should be used to warn oncoming traffic in the event of a vehicle breakdown. Turn on your emergency warning lights. If you do not have warning lights, use your taillights."
• Use your high beams to alert other drivers.
• Stand in front of the vehicle to signal drivers.
• Honk your horn repeatedly.