GM Bonneville/Eighty Eight/LeSabre 1986-1999

Oil Pressure Sender

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OPERATION



The oil pressure sender/switch relays the engine oil pressure to the dash gauge.

TESTING



  1. To test the normally closed oil pressure lamp circuit, disengage the locking connector and measure the resistance between the switch terminal (terminal for the wire to the warning lamp) and the metal housing. The ohmmeter should read 0 ohms.
  2.  
  3. To test the sending unit, measure the resistance between the sending unit terminal and the metal housing. The ohmmeter should read an open circuit (infinite resistance).
  4.  
  5. Start the engine.
  6.  
  7. Once again, test each terminal against the metal housing:
    1. The oil switch terminal-to-housing circuit should read an open circuit if there is oil pressure present.
    2.  
    3. The sending unit-to-housing circuit should read between 15-80 ohms, depending on the engine speed, oil temperature and oil viscosity.
    4.  

  8.  
  9. To test the oil pressure sender only, rev the engine and watch the ohms reading, which should fluctuate slightly (within the range of 15-80 ohms) as rpm increases.
  10.  
  11. If the above results were not obtained, replace the sending unit/switch with a new one.
  12.  

REMOVAL & INSTALLATION



See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. If necessary for access, raise and safely support the vehicle.
  4.  
  5. If necessary, drain the engine oil into a suitable container.
  6.  
  7. Detach the switch electrical connector.
  8.  
  9. Remove the switch.
  10.  



Click image to see an enlarged view

Fig. Fig. 1: Location of the oil pressure switch - 1995 vehicle shown, others similar

To install:
  1. Coat the first two or three threads with sealer. Install the switch and tighten until snug. Engage the electrical lead.
  2.  
  3. Carefully lower the vehicle.
  4.  
  5. Fill the crankcase with the proper type and amount of engine oil.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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