Subaru Coupes/Sedans/Wagons 1985-1996 Repair Guide

Oil Pressure Gauge Switch

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Depending on the model and trim level, an oil pressure gauge may be installed in the vehicle instrument cluster. This gauge uses a separate sensor to register oil pressure.

OPERATION



See Figures 1, 2 and 3

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Fig. Fig. 1: Cutaway view of oil pressure gauge sensor switch



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Fig. Fig. 2: Schematic of oil pressure gauge and sensor with no oil pressure



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Fig. Fig. 3: Schematic of oil pressure gauge and sensor with oil pressure applied

The oil pressure gauge switch monitors the oil pressure at the pump. Depending on the model, it is attached to the oil pump case (1.6L, 1.8L and 2.7L engines) or cylinder head (2.2L, 2.5L and 3.3L engines).

This sensor consists of a moving diaphragm which reacts according to the oil pump pressure, a temperature compensating bimetal, a heat wire and two contacts.

When no oil pressure is presents, the two contact points are open slightly. As oil pressure increases, the point arm begins to contact the bimetal. With the ignition switch ON , current flows to the heat wire in the sensor and begins to create heat which bends the bimetal and point arm in the sensor. As the bimetal in the sensor heats and bends, current is created which is transported through the sensor wire to the gauge, where it begins to heat a bimetal in the gauge. The bending bimetal moves the point arm in the gauge. As the oil pressure changes, it creates a different current flow and resulting generated heat to the bimetal in the sensor and gauge.

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Access the oil pressure sensor on the oil pump case (1.6L, 1.8L and 2.7L engines) or cylinder head (2.2L, 2.5L and 3.3L engines). Unfasten the wire harness from the switch.
  4.  
  5. Place a suitable drain pan underneath the oil pressure sensor to capture any oil which may spill out during the removal and installation of the switch.
  6.  
  7. Use an appropriate wrench to loosen and remove the oil pressure sensor. If reinstalling original oil pressure sensor, remove and discard washer on sensor.
  8.  

To install:
  1. Position the oil pressure sensor and new washer into hole in oil pump case or cylinder head, depending on models, and hand-tighten.
  2.  
  3. Use an appropriate socket and tighten the pressure sensor to 12-17 ft. lbs. (17-23 Nm).
  4.  
  5. Fasten the wire harness to the oil pressure sensor.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Check the oil level and add if needed.
  10.  

 
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