0391421 JOHNSON CLAMP SCREW ASSY.

Illustration 1 g01329056
Component location on a typical C11 or C13 engine (1) Control valve (2) Pressure sensor (3) Check valve (4) Actuators
Illustration 2 g01329140
Component location on a typical C15 engine (1) Control valve (2) Pressure sensor (3) Check valve (4) ActuatorsSystem Operation During Engine StartThe ECM performs the following sequence of operations every time the engine is started:
The ECM commands the control valve to open for 17 seconds.
The ECM checks the temperature of the coolant.
The ECM commands the control valve to close when the coolant temperature exceeds 20 °C (68 °F). This allows the temperature of the oil in the rail to warm up.
The ECM commands the control valve to open. The ECM samples the rail pressure. The ECM commands the control valve to close. The ECM takes a second sample of the rail pressure. The ECM compares the two pressure values. The ECM activates a 2949-7 code if the pressure difference is too low.
The control valve should remain closed during engine operation.System Operation During Engine OperationThe system does not operate until the engine has reached normal operating temperature.
Illustration 3 g01329143
Section view of the components (4) Actuator (5) Space (6) Solenoid (7) Piston (8) Rocker arm (9) Valve (10) Rail (11) Intake valvesEach actuator (4) contains two solenoids (6) . Each solenoid is connected to a valve (9) . The solenoid is normally de-energized. The valve is normally open. This allows oil to flow between rail (10) and the space (5) above piston (7) .Rocker arm (8) is down when the intake valves are open. Pressurized oil flows from rail (10) to space (5) above piston (7) . This causes the piston to move down. The piston contacts rocker arm (8) .The ECM energizes solenoid (6) when the ECM requires intake valves (11) to remain open. The energized solenoid closes valve (9) . This traps the oil in space (5) . The trapped oil causes piston (7) and rocker arm (8) to remain down. This keeps intake valves (11) open.The ECM de-energizes solenoid (6) when the ECM requires the intake valves to close. The de-energized solenoid lifts valve (9) . Valve springs (9) raise intake valves (11) , rocker arm (8) , and piston (7) . The rising piston forces the oil from space (5) and into the rail (10) .The flow of oil into the rail changes the pressure of the oil in the rail. The ECM monitors the rail pressure. The ECM determines if the changes in rail pressure are correct for the commands that were sent to a particular solenoid. The ECM activates a diagnostic code for the appropriate cylinder if the changes in rail pressure are incorrect for that solenoid.Troubleshooting ProcedureUse this procedure to diagnose mechanical problems or electrical problems with the intake valve actuation system. The following diagnostic codes indicate that there is a mechanical problem or an electrical problem with the system:
Table 1
Diagnostic Codes for Mechanical Problems or Electrical Problems with the Intake Valve Actuation System    
J1939 Code    Description    Conditions Which Can Cause The Code    
2949-7     Intake Valve Actuation Oil Pressure not responding     This code can only occur soon after the engine has started.
This code indicates that the difference in rail pressure is incorrect while the control valve is opened and closed. The following conditions can cause this code:
The harness connectors for the pressure sensor and the differential pressure sensor for the combustion air supply are interchanged. This can only occur on certain C15 engines. Refer to Test Step 4.
A control valve that contains debris or a control valve that is not operating correctly
Damaged O-ring seal or missing O-ring seal. The O-ring seals are at location (19) in Illustration 13 and locations (26) and (27) in Illustration 16.    
2950-7     Intake Valve Actuator #1 not responding     The intake valve actuator is not responding correctly to the commands from the ECM. This can be caused by the following conditions:
There is an oil leak in the system.
There is a problem with an actuator.
The valve lash is incorrect.
The adjustment of an actuator is incorrect.    
2951-7     Intake Valve Actuator #2 not responding    
2952-7     Intake Valve Actuator #3 not responding    
2953-7     Intake Valve Actuator #4 not responding    
2954-7     Intake Valve Actuator #5 not responding    
2955-7     Intake Valve Actuator #6 not responding    
2948-18     Engine Intake Valve Actuation System Oil Pressure : Low - moderate severity (2)     There is an oil leak in the system. The following conditions can cause an oil leak:
Chafed or damaged coolant diverter valve harness
Low core engine oil pressure
Refer to table 2 or refer to table 3.
Leaking hose fitting
Damaged face seal or missing face seal
Loose actuator assembly
Loose plug or missing plug on the actuator assembly
Loose control valve or loose sensor
Damaged O-ring seal or missing O-ring seal
Low oil level
The check valve is stuck open. The rail pressure cannot maintain the desired value if the check valve is stuck open.
The control valve remains partially open. This condition allows the oil to continuously leak out of the rail. This condition can be caused by debris or by abuse. These conditions hinder the movement of the valve's internal components. If the control valve is partially open, a 2949-7 code is usually activated in addition to the 2948-18 code.    
Follow the troubleshooting procedure in order to identify the root cause of the problem.    Note: Resolve any electrical problems with the system before you use this procedure.SymptomsThe following symptoms may occur if there is a problem with the intake valve actuation system.
Intermittent check engine light
Intermittent reductions in engine powerYou may need to perform a road test in order to verify that the problem is resolved. If a road test is performed on the engine, the