C13, C15, and C18 Engines Troubleshooting – Variable Valve Actuator – Test

System Operation Description:

Table 1 lists the diagnostic trouble codes that are covered by this procedure. Also, use this procedure if you have been directed from Troubleshooting, “Symptom Troubleshooting”.

Table 1
Diagnostic Trouble Codes for the Intake Valve Actuators
J1939 Code CDL Code Description Information
2950-5 1901-5 Engine Intake Valve Actuator #1 : Current Below Normal The ECM monitors the current flow through the circuit for each actuator. If low current flow (open circuit) is detected, a -5 diagnostic code is activated. The ECM continues to try to activate the actuator. If high current flow (short circuit) is detected, a -6 diagnostic trouble code is activated. The ECM will disable the solenoid circuit in order to prevent damage from the high current flow. However, the ECM will periodically try to activate the actuator. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.

The ECM takes the following actions while the code is active:

Engine power is derated by ten percent.

The amber warning lamp is illuminated.

These codes are usually caused by a wiring problem. The wiring problem can be on the outside of the engine or underneath the valve cover.

2950-6 1901-6 Engine Intake Valve Actuator #1 : Current Above Normal
2951-5 1902-5 Engine Intake Valve Actuator #2 : Current Below Normal
2951-6 1902-6 Engine Intake Valve Actuator #2 : Current Above Normal
2952-5 1903-5 Engine Intake Valve Actuator #3 : Current Below Normal
2952-6 1903-6 Engine Intake Valve Actuator #3 : Current Above Normal
2953-5 1904-5 Engine Intake Valve Actuator #4 : Current Below Normal
2953-6 1904-6 Engine Intake Valve Actuator #4 : Current Above Normal
2954-5 1905-5 Engine Intake Valve Actuator #5 : Current Below Normal
2954-6 1905-6 Engine Intake Valve Actuator #5 : Current Above Normal
2955-5 1906-5 Engine Intake Valve Actuator #6 : Current Below Normal
2955-6 1906-6 Engine Intake Valve Actuator #6 : Current Above Normal
Follow the troubleshooting procedure in order to identify the root cause of the problem.

System Operation During Engine Operation

The intake valve actuation system does not operate until the engine has reached normal operating temperature. Also, the engine must meet certain operating conditions in order to activate the intake valve actuation system.

There are three housings under the valve cover. Each housing contains two actuators. There is a solenoid for each actuator. The ECM sends a command to a solenoid when the ECM requires the intake valves for a cylinder to remain open. The ECM monitors the current flow through the circuit for the solenoid. The ECM activates a diagnostic code if the current flow is below normal or above normal.

“Intake Valve Actuator Solenoid Test”

This test is available on the Caterpillar Electronic Technician (ET). The test helps diagnose problems with the circuits for the solenoids. The following conditions must be met before the test will function:

 

  • Engine speed must be zero.
  • Vehicle speed must be zero.
  • The transmission gearshift lever must be in neutral.


Illustration 1 g02300033
Schematic for the C15 engine


Illustration 2 g01185728
P2 terminals for the intake valve actuators

(18) Actuator 4 return

(21) Actuator 5 return

(22) Actuator 2 return

(31) Actuator 3 return

(42) Actuator 6 return

(50) Actuator 1 return

(58) Actuator 5 & 6 supply

(67) Actuator 3 & 4 supply

(68) Actuator 1 & 2 supply

Table 2
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring

A. Check the engine harness between the P2 connector and the connectors near the grommets. Look for the following problems:

1. Moisture
2. Loose connectors or damaged connectors
3.Damage that is caused by excessive heat
4. Damage that is caused by chafing
5. Improper routing of wiring
6. Damaged insulation

B.Inspect the connectors near the grommets. The connectors must be clean and dry.

C. Perform a 45 N (10 lb) pull test on each of the wires in the connectors. This test verifies that the wire is properly crimped to the terminal and that the terminal is properly inserted into the connector.

Moisture

Damage to connectors

Result: The wiring is OK.

If you are troubleshooting a -5 code, proceed to Test Step 2.

If you are troubleshooting a -6 code, proceed to Test Step 4.
Result: The wiring is not OK.

Repair the wiring problem. Replace parts, if necessary. Perform the “Intake Valve Actuator Solenoid Test”.

If all of the actuators pass the test, troubleshooting is complete. Return the unit to service.

2. Short the External Wiring Harness

A.Connect a jumper wire to the engine harness connector. Connect the jumper wire between the appropriate terminals for the supply and for the return of the suspect actuator.
The jumper will replace the actuator and the valve cover wiring harness with a short circuit. Refer to Illustration 1 or Illustration 2.

B. Perform the “Intake Valve Actuator Solenoid Test”. Determine the test result for the suspect cylinder.

Short Circuit indicated Result: The test result indicated “Not Active: Device Open” for the suspect cylinder.
The ECM did not detect the jumper wire. There is an open circuit in the wiring between the valve cover connector and the P2 connector. There may be a problem inside a connector.

Repair the wiring problem. Replace parts, if necessary. Connect all of the electrical connectors.
Perform the “Intake Valve Actuator Solenoid Test”. Verify that all of the cylinders pass the test.

Result: The test result indicated “Not Active: Device Short” for the suspect cylinder.
The ECM detected the jumper wire. The external engine wiring harness is OK.
proceed to Test Step 3.

3. Inspect Wiring Under the Valve Cover

A. Remove the valve cover. Look for these problems:

1. Loose connectors or damaged connectors
2.Damage that is caused by excessive heat
3. Damage that is caused by chafing
4. Improper routing of wiring
5. Damaged insulation

Repair any wiring problems. Replace parts, if necessary.

Connect all of the electrical connectors.

Perform the “Intake Valve Actuator Solenoid Test”.

Damage to wires or connectors Result: The suspect cylinder passed the test. the problem is resolved.

Return the engine to service.

Result: The suspect cylinder failed the test.
Replace the appropriate actuator housing.

Verify that all actuators pass the “Intake Valve Actuator Solenoid Test” after the new housing is installed.

Return the engine to service.

4. Create an Open in the External Wiring Harness

A. Disconnect the appropriate connector near the grommets. This will replace the actuator and the valve cover wiring harness with an open circuit.

Refer to Illustration 1 or Illustration 2.

B. Perform the “Intake Valve Actuator Solenoid Test”. Determine the test result for the suspect cylinder.

Open Circuit Result: The test result indicated “Not Active: Device Short” for the suspect cylinder.
The ECM did not detect the open circuit. There is a short circuit in the wiring between the valve cover connector and the P2 connector. There may be a problem inside a connector.
Repair the wiring. Replace parts, if necessary.
Connect all of the electrical connectors and perform a “Intake Valve Actuator Solenoid Test”. Verify that all of the cylinders pass the test.

Result: The test result indicated “Not Active: Device Open” for the suspect cylinder. The ECM detected the open circuit. The external engine wiring harness is OK.

Proceed to Test Step 5.

5. Inspect Wiring Under the Valve Cover

A. Remove the valve cover. Look for these problems:

1. Loose connectors or damaged connectors
2.Damage that is caused by excessive heat
3. Damage that is caused by chafing
4. Improper routing of wiring
5. Damaged insulation

Repair any wiring problems. Replace parts, if necessary.

Connect all of the electrical connectors.

Perform the “Intake Valve Actuator Solenoid Test”.

Damage to wires or connectors Result: The suspect cylinder passes the test, the problem is resolved. STOP.

Result: The suspect cylinder failed the test.
Replace the appropriate actuator housing. Verify that all actuators pass the “Intake Valve Actuator Solenoid Test” after the new housing is installed.

Test Step 1.

Complete the procedure in the order in which the steps are listed.

Results:

 

  • The procedure corrected the issue. – STOP 
  • The procedure did not correct the issue. –Repair: Contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).

    STOP

 

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