Jeep Wagoneer/Commando/Cherokee 1984-1998

Oil Pressure Sending Unit

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TESTING



  1. To test the normally closed oil 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

Click image to see an enlarged view

Fig. Fig. 1: View of the oil pressure sending unit removal

  1. Disconnect the negative battery cable from the battery.
  2.  
  3. Unplug the oil pressure sending unit wiring harness connector from the sending unit.
  4.  
  5. Unscrew the sending unit from the engine block.
  6.  

To install:
  1. Install and tighten the new sending unit.
  2.  
  3. Plug the electrical wiring harness into the sending unit.
  4.  
  5. Attach the negative battery cable.
  6.  

 
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