Combination Oil Sending Unit Test
NOTE:
Combination oil sending unit provides an on/off switch for oil pressure warning light. Normally closed switch will keep oil pressure warning light on until there is oil pressure. Combination oil sending unit also provides a resistance that varies with oil pressure.
- With engine off, locate and disconnect combination oil sending unit connector. See Fig 1 . To check low oil pressure switch portion of combination oil sending unit, measure resistance between appropriate switch terminal and metal housing of sending unit. See Fig 2 .
- Reading should be zero ohms. If reading is not zero ohms, replace sending unit. If reading is correct, start engine. Ohmmeter should read open circuit with oil pressure present. Replace sending unit if either reading is not as specified.
- Turn engine off. To check oil pressure sending unit portion of combination oil sending unit, measure resistance between sending unit and metal housing. Ohmmeter should indicate open circuit with engine off. Start engine. Ohmmeter should read 30-55 ohms, depending on engine speed, oil temperature and oil viscosity. If reading is not within specification, replace sending unit.