The phrase "warning triangle" refers to a triangular-shaped sign that is used to warn other people, usually drivers, about a dangerous situation or hazard ahead. Full definition
In order to notify other vehicles of the car's presence, an emergency warning triangle is made available. (cardekho.com)
ROADSIDE ASSISTANCE KIT - inc: booster cables warning triangle LED flashlight work gloves PVC tape multi-tool blanket poncho whistle cable ties and bandages (stevenscreekvw.com)
Lane Watch takes the place of automated blind spot detection systems that gauge the distance for you and give you a go / no - go indicator in the outside mirror or window frame, often a steady yellow warning triangle when a car is in your blind spot, that flashes (sometimes accompanied by a steering wheel vibration or warning beep) if you flip the turn signal. (extremetech.com)