Oil Pressure Switch

Today is about engine We are going to cover in details about engine oil pressure switch operating principles and diagnostic in this article today.

Oil Pressure Switch
Figure 1
  • Introduction of the oil pressure switch
  • Operating principles
  • Diagnostic and testing procedures
  • Testing procedures with a multimeter

Introduction of oil pressure switch

Oil pressure switches are typically used as an actuator which directly activates the oil warning light and Driver dashboard when the oil pressure in the engine will fall below the preset critical level or brings a signal to the ECU engine control unit to be warned about the low pressure of engine oil and prevent damage to the engine depending on the engine.

Construction of the oil pressure switch usually can be found in one of the most common locations in the cylinder block of the engine or the oil filter housing as well as that some engine types can be found in the engine head.

Operating principles

Oil Pressure Switch

The switch is operated by a self elastic diaphragm or movable diaphragm with fitted hairspring whose position is determined by the pressure applied to it the required critical pressure for moving up the diaphragm and activating switching on or switching off the switch contacts is determined by the oil pressure of the engine.

This critical value of oil pressure is individual for every engine type and can vary usual value is between 0.25 and 0.75 bar(3.5-11 psi)

If the oil pressure falls below this critical value the switch directly activates the oil warning light and Driver dashboard or in some engine management systems the switch returns a signal to the ECU so to be warned about the low pressure of engine oil and prevent damage to the engine the switch contacts can be either normally open or normally closed

  1. Washer for sealing
  2. Diaphragm
  3. Switch housing
  4. Connector
  5. Switch contacts and normally open be normally closed
  6. Thread for tightness

The figure 1 under A shows an illustrative drawing of one type of oil pressure switch with normally open contacts and under B type of switch with normally closed contacts the operation of these types of switches is fundamentally similar in all instances although the type, size and construction can vary upon the manufacturer application or requirement of a used system.

At the switches with normally open contacts when the engine oil pressure reaches the present critical level produces movement of the diaphragm and activates the contacts of the switch so the contacts are connected together that is the switch is closed (switched on).

The switches with normally closed contacts work opposite when the engine oil pressure reaches the preset critical level deactivates the already connected contacts of the switch so now the contacts are disconnected that is the switch is open (switched off).

Diagnostics and testing procedures

Oil Pressure Switch

Switch with normally open contacts

  1. Check that there is an open circuit between the contacts when the engine is not running
  2. See carefully that there is a short circuit continuity between the contacts when the engine is running
  3. See that there is a short circuit continuity between the contacts when the engine is running
  4. Check the continuity and condition of the pins terminals and wires
  5. See that there is a short-circuit continuity between the contacts when the engine is not running
  6. Check that there is an open circuit between the contacts when the engine is running
  7. Check the continuity and condition of the pins terminals and wires

Testing procedures with a multimeter

Unplug the connector from oil pressure switch and check the connectivity between the contacts if the switch is with two pins the check should be between the pins in case when the switch is with only one pin then the check should be between the pin and mass

Negative pole when the engine is not running the read value of the electrical resistance from the multimeter in case of the switch with normally open contacts should be infinite contacts are disconnected switched off and in case of the switch with normally closed contacts should be zero contacts are connected (switched on)Features.

Features of an OPS oil Oil Pressure Switch

  1. Robust ceramic sense element
  2. Many ports, material, and connector options
  3. High accuracy over temperature and pressure
  4. >40M in the field since 2002
  5. Analog or SENT, P+T combo optional

Benefits of Oil Pressure Switch/ Sensor

  1. Better control of variable flow pumps
  2. Expand use of VVT, VVL, CYL-DEACT
  3. Detect low oil pressure
  4. Feedback for OBD systems
  5. High reliability, low risk
  6. Global manufacturing scale, redundancy

When the engine is running the read value of the electrical resistance from the multimeter in case of the switch with normally open contacts should be zero contacts are connected switched on and in case of the switch with normally closed contacts should be infinite. (contacts are disconnected switched off) if you enjoyed reading this provide your comment below, thank you

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