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oil pressure sensor vs switch
The function of the oil pressure switch is to detect the engine oil pressure and feedback the signal to the CPU. Upon receiving an abnormal signal, the CPU will control an alarm on the display screen, and at the same time, the buzzer will alarm. The sliding resistance type oil pressure sensor is used to detect the magnitude of engine oil pressure. It is usually screwed into the oil duct of the cylinder block.
Its working principle is that the oil pressure sensor has a variable resistor inside, which outputs a signal at one end and is connected to a grounded sliding arm at the other end. When the oil pressure increases, the oil pressure pushes the diaphragm to bend through the lubrication oil channel interface, and the diaphragm pushes the sliding arm to move to a low resistance position, increasing the output current in the circuit; On the contrary, the diaphragm pushes the sliding arm to move to a high resistance position, reducing the output current in the circuit, and ultimately indicating the magnitude of the oil pressure on the oil pressure gauge with a pointer. The engine oil pressure alarm switch is usually installed on the main oil duct of the engine cylinder block to detect the magnitude of the engine oil pressure value. When it falls below a certain specified value, the engine oil pressure warning light is turned on. The oil pressure switch consists of a spring, diaphragm, and contacts. When there is no oil pressure or low pressure, the spring pushes the diaphragm and the contacts are in the (ON) closed state; When the specified pressure is reached, the diaphragm overcomes the spring force and causes the contact to open (OFF).
The working principle of the oil pressure indicator (oil pressure warning light):
The oil pressure indicator light is installed in the combination instrument panel, and the pressure switch is installed on the engine lubricating oil circuit. Inside the pressure switch, there is a diaphragm operated by oil pressure and a contact operated by oil pressure. When the oil pressure is lower than the specified value, the diaphragm does not have the force to push the spring, the contact is closed, and the indicator light is on; When the oil pressure exceeds the specified value, the diaphragm pushes up the spring, the contacts separate, and the indicator light goes out, informing the driver that the oil pressure has reached the specified value. Normally, the contact action pressure is within the range of 30-50kPa. The detection method for the oil pressure switch is as follows: After the ignition switch is turned on, the oil pressure indicator light does not light up. The reason for the fault is that the wiring harness of the oil pressure indicator light has fallen off, or the filament has blown, or the fuse has blown. After the engine starts, the oil pressure reaches the specified value, and the oil pressure indicator light lights up. The cause of the fault is poor contact switch action or wiring harness grounding.
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