GM Lumina/Silhouette/Transport APVs 1990-1999 Repair Guide

Oil Pressure Sensor



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


If low oil pressure is suspected, because the dash light is on or the indicator gauge on the dash reads low the oil pressure can be checked on the vehicle using the following procedure; however, it will require the use of a special tool.

  1. Check the oil level, bring it to the full mark.
  3. Remove the oil filter. Expect to lose some oil, as it will drip from the oil filter and filter mounting pad.
  5. Assemble the plunger in the large hole of the tester base and the hose in the small hole of the tester base. Connect the gauge to the end of the hose.
  7. Insert the flat side of the rubber plug, for ease of installation, in the by-pass valve itself.
  9. Install the tester on the filter mounting pad.
  11. Start the engine to check the overall pressure, sender switch, or noisy lifters. Engine should be at operating temperature before taking an oil pressure reading. Look for a pressure reading of about 60 psi (414kPa) @ 1850 RPM, if the engine has 10W-30 oil in it.
  13. If adequate oil pressure is indicated, replace the pressure sending switch.
  15. If a low reading is indicated, depress the valve on the tester base to isolate the oil pump and/or its components from the lubricating system. An adequate reading at this time would indicate a good pump and the previous low pressure was due to worn bearings, etc. A low reading while depressing the valve would indicate a faulty pump.