How to Test a Single-Wire Oil Pressure Switch?
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After the ignition switch is turned on, if the oil pressure indicator light does not illuminate, the possible causes are that the wiring harness of the oil pressure indicator has come loose, the filament has burned out, or the fuse has blown. After the engine is started, if the oil pressure reaches the specified value and the oil pressure indicator light turns on, the fault may be due to poor operation of the contact switch or a grounded wiring harness. Below are additional details: 1. Oil Pressure Range: When the oil pressure is below the specified value, the diaphragm does not exert enough force to push the spring, causing the contacts to close and the indicator light to illuminate. When the oil pressure exceeds the specified value, the diaphragm pushes the spring, separating the contacts and turning off the indicator light, notifying the driver that the oil pressure has reached the required level. Typically, the contact activation pressure ranges between 30~50 kPa. 2. Principle: The engine oil pressure sensor is designed to measure the oil pressure in the engine. It is usually screwed into an oil passage in the cylinder block. Inside the oil pressure sensor, there is a variable resistor with one end outputting a signal and the other end connected to a sliding arm that is grounded.