Cylinder Deactivation (Active Fuel Management) Valve Lifter Oil Manifold Diagnosis and Testing

Special Tools

• EN-46999:  Active Fuel Management Tester
• EN-46999-1:  Active Fuel Management Tester Air Adapter
• EN-46999-5:  Active Fuel Management Tester Harness - Small Block V8

For equivalent regional tools, refer to Special Tools 

Fig 1: Identifying Displacement On-Demand Tester

Courtesy of GENERAL MOTORS CORP.

The manifold bench test provides a maximum 206 kPa (30 psi) of filtered shop air to the manifold and will test each solenoid/valve for the following conditions:

• Proper operation
• A stuck open condition - constant air flow
• A stuck closed condition - no air flow
• A flow restriction within the manifold

1. Individually depress each of the buttons 1-4 on the EN-46999:  tester in order to activate each of the solenoid/valves. When activating each solenoid/valve, a loud click should be heard from the solenoid and an increased amount of air will exit the outlet ports.
   • Button 1 will energize the solenoid/valve 1 for engine cylinder number 1.
   • Button 2 will energize the solenoid/valve 2 for engine cylinder number 4.
   • Button 3 will energize the solenoid/valve 3 for engine cylinder number 6.
   • Button 4 will energize the solenoid/valve 4 for engine cylinder number 7.
Fig 2: Valve Lifter Oil Manifold
Courtesy of GENERAL MOTORS CORP.
2. Do not lift the manifold assembly by the electrical lead frame.
Fig 3: Displacement-on-Demand Tester Air Adapter
Courtesy of GENERAL MOTORS CORP.
3. Install the EN-46999-1:  adapter (1) to the manifold.
CAUTION: Refer to Fastener Caution .
4. Install 2 of the manifold bolts (2) to the EN-46999-1:  adapter and tighten to 25 N.m (18 lb ft).
Fig 4: Connecting Air Out Hose
Courtesy of GENERAL MOTORS CORP.
5. Connect the air out hose (2) of the EN-46999:  tester (5) to the EN-46999-1:  adapter (1). Verify the air supply switch (4) is in the off position.
6. Connect the air in hose (6) of the EN-46999:  tester (5) to a shop air source.
7. Connect the 12-volt power supply connectors (7) of the EN-46999:  tester (5) to a 12-volt power supply. Verify the Power light (8) on the tool is illuminated. If the light on the tool is not illuminated when connected to a 12-volt power supply, test and/or replace the 3 amp fuse.
8. Connect the EN-46999-5:  harness power cable (3) to the electrical connector of the manifold.
Fig 5: Bleed Holes & Outlet Ports
Courtesy of GENERAL MOTORS CORP.
9. Turn the air supply switch of the EN-46999:  tester to the ON position. With the air supply connected to the manifold assembly and the solenoid/valves in the closed position, a limited amount of air will exit each of the bleed holes (3) and outlet ports (1, 2) of the manifold.
Fig 6: Testing Solenoid/Valves
Courtesy of GENERAL MOTORS CORP.
NOTE: The manifold must be tested in the proper position to ensure the solenoid/valves operate as designed.
10. Position the manifold assembly onto a bench at a 45 degree angle in order to test solenoid/valves 1 and 4.
11. Depress button number 1 on the tool to activate solenoid/valve 1. With button 1 depressed, the solenoid/valve (1) should open, allowing an increased amount of air to exit the outlet ports (2) of the manifold.
12. Depress button number 4 on the tool to activate solenoid/valve 4. With button 4 depressed, the solenoid/valve (4) should open, allowing an increased amount of air to exit the outlet ports (3) of the manifold.
Fig 7: View Of Solenoid/Valves 2 & 3
Courtesy of GENERAL MOTORS CORP.
13. Reposition the manifold assembly onto a bench at a 45 degree angle in order to test solenoid/valves 2 and 3.
14. Depress button number 2 on the tool to activate solenoid/valve 2. With button 2 depressed, the solenoid/valve (2) should open, allowing an increased amount of air to exit the outlet ports (4) of the manifold.
15. Depress button number 3 on the tool to activate solenoid/valve 3. With button 3 depressed, the solenoid/valve (3) should open, allowing an increased amount of air to exit the outlet ports (1) of the manifold.
16. When the test is completed, turn the air source switch on the EN-46999:  tester to the off position and disconnect the tool from the 12-volt power supply, shop air source and manifold assembly.
17. If after testing, it has been determined that 1 or more of the solenoid/valves is not functioning properly, replace the manifold as an assembly.
18. If after testing, it has been determined that the solenoid/valves are functioning properly, replace the valve lifters, as required. Both intake and exhaust lifters should be replaced in pairs.