Chevrolet Silverado / GMC Sierra. Service manual — part 1881

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

CYLINDER DEACTIVATION (ACTIVE FUEL MANAGEMENT) OIL PRESSURE RELIEF VALVE
VALVE DIAGNOSIS AND TESTING

Tools Required

EN-47971 Oil Pressure Gage Adapter. See Special Tools.

J 21867 Pressure Gage. See Special Tools.

J-21867-16 Oil Pressure Adapter. See Special Tools.

Diagnosis and Testing

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Fig. 19: View Of Special Tools: Oil Pressure Gage & Adapter
Courtesy of GENERAL MOTORS CORP.

IMPORTANT:

Cylinder Deactivation (Active Fuel Management) Oil
Pressure Relief Valve Diagnosis and Testing is
applicable for RPO LH6/LMG/LY5/LC9/L76.

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 and Lubrication

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

1. Remove the oil filter and install the EN-47971 (1). See Special Tools.

2. Install the J 21867 (2), or equivalent, to the EN-47971 (1). See Special Tools.

Fig. 20: View Of Oil Pressure Sensor
Courtesy of GENERAL MOTORS CORP.

3. Remove the oil pressure sensor and install the J-21867-16 . See Special Tools.

Description (RPO LY2) or Lubrication Description (RPO
LH6/LMG/LY5/LC9) or Lubrication Description (RPO
LY6/L92) or Lubrication Description (RPO L76).

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

Fig. 21: Measure Engine Oil Pressure
Courtesy of GENERAL MOTORS CORP.

4. Install the J 21867 (1), or equivalent, to the J-21867-16 (2). See Special Tools.

5. Run the engine and measure the engine oil pressure while observing both gages.

Operate the throttle, as required, to increase and decrease the engine oil pressure.

With the engine running and the lower pressure gage (2) measuring below 379 kPa (55
psi), both gages should display the same pressure reading. If the readings are not the

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado