Need to identify make and model of the truck, since they don't all use the same instrument panels. It sounds like you're referring to a Volvo dash light which comes on when there isn't enough air pressure built up to hold off the spring brakes, although I don't recall it being upside-down.
Lambda sensors. The 3 leg symbol (upside down 'Y') is the greek lambda symbol
mass fire
Mass Fire
It is still a triangle.
rhombus
The upside down purple triangle was actually used to identify Jehovah's Witnessess
An upside-down triangle. It does not matter from which direction you view a triangle, it will still be a triangle.
The upside-down orange triangle with the number three in the middle represents a fire hazard that indicates a moderate level of flammability. This classification is part of the National Fire Protection Association (NFPA) labeling system, where the number indicates the degree of risk, with three signifying that the material can ignite under most ambient conditions and requires special precautions during handling and storage.
In mathematics an upside down triangle corresponds to the gradient operator and is sometimes called "del". The Greek symbol of an upside down triangle is called "Nabla".
An upside-down orange triangle with the number three indicates a fire hazard related to the storage of materials that can ignite easily, specifically flammable solids. This symbol is commonly used in the context of hazardous materials and signifies that the material can pose a significant risk in a fire situation. It is crucial to handle such materials with care and follow safety protocols to mitigate fire risks.
at the top. The "base" of a triangle is arbitrary.
Upside down triangle bro ;)