Medical Definition of adhesive. 1: an adhesive substance; especially : a substance (as glue, starch, paste, or mucilage) that bonds two materials together by adhering to the surface of each.
The sensors physically measure the tire pressure in each tire and report it to the vehicle's instrument cluster or a corresponding monitor. Some units also measure and alert temperatures of the tire as well. These systems can identify under-inflation in any combination, be it one tire or all, simultaneously.
The Manifold Absolute Pressure (MAP) sensor is used by the Powertrain Control Module (PCM) for engine load input. The PCM uses this input, as well as others, to calculate the correct amount of fuel to inject into the cylinders. The MAP sensor measures the absolute pressure inside the intake manifold of the engine. At sea level, atmospheric pressure is about 14.7 psi (pounds per square inch). When the engine is off, the absolute pressure inside the intake equals atmospheric pressure, so the MAP will indicate about 14.7 psi. At a perfect vacuum, the MAP sensor will read 0 psi. When the engine is running, the downward motion of the pistons create a vacuum inside the intake manifold (For the purposes of engine control, when a technician says vacuum, what they are really saying is pressure that is less than atmospheric pressure).