Cylinder Deactivation (Active Fuel Management) Oil Pressure Relief Valve Diagnosis and Testing

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Special Tools

EN-47971: Oil Pressure Gauge Adapter
J 21867: Pressure Gauge
J-21867-16: Oil Pressure Adapter

For equivalent regional tools, refer to Special Tools .

Fig 1: View Of Special Tools Oil Pressure Gage & Adapter

Courtesy of GENERAL MOTORS CORP.

NOTE:

Cylinder Deactivation (Active Fuel Management) Oil Pressure Relief Valve Diagnosis and Testing is applicable for RPO LH6/LMG/LY5/LC9/L76/LY2/LY6/L9H.
This test is performed to verify the operation of the active fuel management oil pressure relief valve located in the oil pan. Refer to Cylinder Deactivation (Active Fuel Management) System Description andLubrication Description (with Active Fuel Managment) or Lubrication Description (without Active Fuel Management) .

Remove the oil filter and install the EN-47971: gauge adapter (1).
Install the J 21867: gauge (2), or equivalent, to the EN-47971: gauge adapter (1).

Fig 2: View Of Oil Pressure Sensor

Courtesy of GENERAL MOTORS CORP.

Remove the oil pressure sensor and install the J-21867-16: adapter.

Fig 3: Measuring Oil Pressure While Observing Both Gages

Courtesy of GENERAL MOTORS CORP.

Install the J 21867: gauge (1), or equivalent, to the J-21867-16: adapter (2).
Run the engine and measure the engine oil pressure while observing both gauges.
Operate the throttle, as required, to increase and decrease the engine oil pressure.
- With the engine running and the lower pressure gauge (2) measuring below 379 kPa (55 psi), both gauges should display the same pressure reading. If the readings are not the same and the lower gauge (2) has a higher reading, the active fuel management oil pressure relief valve is stuck in the open position or the valve lifter oil manifold filter is plugged.
- With the engine running and the lower pressure gauge (2) measuring above 379 kPa (55 psi), the upper gauge (1) should display no greater than 379-517 kPa (55-75 psi). If the reading on the upper gauge (1) is greater than 517 kPa (75 psi), the active fuel management oil pressure relief valve is stuck in the closed position.
Repair, as required.