C27 Petroleum Generator Set Engines Caterpillar

The balance valve actuator is used to control the actuation of the balance valves. The balance valves control the bypass of exhaust gas between the turbine wheels that are within the asymmetric turbocharger. Equalizing the pressure between the turbine wheels helps to reduce the possibility that the turbocharger will overspeed during engine operation.

Use this procedure to troubleshoot the following codes:

The balance valve actuator and balance valve solenoid are integral components. The valve is designed with a normally open position. As the solenoid is energized, the valve is closed. Air flow to the diaphragms of the balance valves at the turbochargers is restricted. The valve vents residual air pressure that is in the air lines to the atmosphere.

In order to test the balance valve actuator, a test apparatus that consists of the following tooling will be required:

Illustration 1	g02140483
Schematic for the balance valve solenoid

Test Step 1. Check for Diagnostic Trouble Codes

1. Establish communication between Caterpillar Electronic Technician (ET) and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.

2. Determine if a code is active or logged.

Results:

• No Active Codes - There are no codes active for the balance valve solenoid at this time, but operation of the balance valve actuator is suspect. Proceed to Test Step 2.

• 5276-7 Active - The ECM has determined that the operation of the balance valve actuator is suspect. Proceed to Test Step 2.

• 5276-5 Active - A 5276-5 is active or logged. There is a low current in the circuit for the balance valve solenoid. Proceed to Test Step 9.

• 5276-6 Active - A 5276-6 is active or logged. There is a high current in the circuit for the balance valve solenoid. Proceed to Test Step 8.

Test Step 2. Inspect the Air Lines from the Balance Valve Actuator to the Balance Valves at the Turbochargers

Illustration 2	g02139266
Inspection points for the balance valve air lines

Inspect the air lines from the outlet of the balance valve actuator to the inlet of each of the balance valves for leakage.

Expected Result:

The lines are in good repair.

Results:

• OK - The lines are not damaged. All of the line fittings are clean and tight. Proceed to Test Step 3.

• Not OK - Damage to the lines is discovered.

  Repair: Repair the line or replace the line. Return the unit to service.

  STOP

Test Step 3. Inspect the External Linkage for the Balance Valves at each Turbocharger

Illustration 3	g02139372
Inspection points for the balance valve linkage

1. Inspect the balance valve linkage from each of the canisters to the housing. Also, inspect the connection point from the canister to the valve. Inspect the linkage for the following issues.

   • Dirt buildup

   • Rubbing

   • Damage

Expected Result:

The linkage from the canister to the valve is in good repair.

Results:

• OK - The linkage is not damaged. Proceed to Test Step 4.

• Not OK - The linkage is damaged.

  Repair: Replace the turbocharger. Return the unit to service.

  STOP

Test Step 4. Install the Test Apparatus and Check the System with Pressurized Air

Illustration 4	g02139379
(1) Pressurized air supply (2) Pressure regulator (3) Gate valve (4) Pressure gauge (5) Balance valve solenoid (6) Exhaust balance valve (7) Gate valve

1. Use the parts that are listed in Table 2 to assemble the test apparatus. Refer to Illustration 4 for the proper assembly.
   Show/hide table

   Illustration 5	g02139660
   Test apparatus that is fully assembled

2. Connect the test apparatus between the inlet of the regulated air supply and inlet of the balance valve canister.

   Note: Do not exceed 138 kPa (20 psi) of air pressure to the balance valve canister. Damage to the balance valve diaphragm may occur if this pressure is exceeded.

3. Regulate the supply air pressure for the test apparatus to 138 kPa (20 psi).

4. Loosen the line fitting on the line that exits the balance valve actuator.

5. Check for pressurized air that is leaking from the loose fitting.

   If pressurized air is leaking from the fitting, the balance valve actuator is not stuck in the closed position.

6. Tighten the line fitting.

7. Visually inspect each of the balance valve linkages at the turbocharger for activation.

   While the pressurized air is applied to the system, the balance valve linkage will be fully extended.

Expected Result:

Pressurized air leaks through the fitting during the test and the balance valve linkage is fully extended.

Results:

• OK - Pressurized air leaks through the fitting and the balance valve linkage are fully extended during the test. The valve actuator is not stuck in the closed position. The balance valve linkage is operating correctly. Proceed to Test Step 5.

• Not OK - Pressurized air did not leak from the line at the balance valve actuator and/or the balance valve linkage did not extend fully.

  Repair: If pressurized air did not leak from the line at the balance valve actuator during the test, replace the faulty balance valve actuator. Return the unit to service.

  If the balance valve linkage did not extend fully during the test, there may be a problem with the valve. Proceed to Test Step 7.

Test Step 5. Use the Override to Test for Proper Operation of the Balance Valve Actuator

1. Connect Cat ET. Proceed to the "Diagnostic Overrides" screen on Cat ET.

2. Restore electrical power to the ECM.

3. Ensure that the supply air pressure to the test apparatus is regulated to 138 kPa (20 psi). Ensure that the test apparatus is attached to the inlet of the balance valve actuator.

4. Use Cat ET to activate the "Engine Exhaust Manifold Bank #1 Flow Balance Valve Solenoid Override". The balance valve actuator will close.

5. While the override is active, close the gate valve on the test apparatus for the pressurized air. The system will be isolated from the regulated air supply.

6. While the override is active and the air supply is isolated, use the other gate valve to vent the pressure in the test apparatus.

7. Ensure that both gate valves are in the CLOSED position. The air lines group and diaphragm valves will be isolated from the regulated air supply and the atmospheric air.

8. Allow the override to remain active for a test period of 90 seconds.

9. At the end of the test period, deactivate the override. The balance valve actuator will open.

10. Read the gauge pressure from the test apparatus.

11. Remove the test apparatus. Restore the system to the original configuration.

Expected Result:

The test results indicate that the system maintained pressure during the test.

Results:

• OK - The system maintained pressure during the test. The air lines and the balance valve diaphragms are maintaining pressure. Proceed to Test Step 6.

• Not OK - The system did not maintain pressure during the test.

  Repair: There is an air leak in the lines group or in a balance valve diaphragm at the turbocharger. Locate the leak. Perform the necessary repairs. Verify that the problem has been resolved. Return the unit to service.

  STOP

Test Step 6. Check the Condition of the Retractor Springs at the Turbocharger

1. Ensure that all air pressure is removed from the test apparatus.

2. Attempt to move the balance valve linkage by hand.

Expected Result:

The linkage cannot be moved by hand.

Results:

• OK - The linkage will not move by hand. The spring appears to be OK. Proceed to Test Step 7.

• Not OK - The linkage is easily moved.

  Repair: There is not an appropriate spring tension on the valve assembly. Replace the turbocharger. Return the unit to service.

  STOP

Test Step 7. Inspect the Internal Components of the Valve at the Turbocharger

Illustration 6	g02140410
Location of the cover at the turbocharger

1. Ensure that the pressurized air supply has been removed from the test apparatus.

2. Remove the cover from the turbocharger housing.

3. Check the condition of the internal components.

Expected Result:

The internal components for the valve are in good repair.

Results:

• OK - The internal components are in good repair.

  Repair: There does not appear to be a problem with the balance valve system. Return the unit to service.

  STOP

• Not OK - There is evidence of a problem with the internal components of the valve.

  Repair: Replace the turbocharger. Verify that the repair has resolved the original problem. Return the unit to service.

  STOP

Test Step 8. Create an Open Circuit at the Harness Connectors for the Balance Valve Solenoid

1. Remove electrical power from the ECM.

2. Disconnect the connectors for the balance valve solenoid.

3. Restore the electrical power to the ECM.

   Note: The ECM can only detect an open circuit condition on this circuit when the output driver is not activated.

4. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

5. Remove electrical power from the ECM. Leave the connectors for the balance valve solenoid disconnected.

Expected Result:

A -5 code became active for the balance valve solenoid during the test.

Results:

• OK - The active code changed from a -6 code to a -5 code.

  Repair: The circuit for the solenoid is OK. There is a problem with the solenoid. Temporarily connect a new solenoid to the harness, but do not install the new solenoid. Verify that there are no active codes for the balance valve solenoid.

  If there are no active codes for the NRS, permanently install the new solenoid. Clear any logged diagnostic codes.

  STOP

• Not OK - The -6 code remains active while both of the connectors is disconnected. The short is in the harness between the connector for the solenoid and the ECM. There may be a problem with the ECM. Leave the connectors for the solenoid disconnected. Proceed to Test Step 10.

Test Step 9. Create a Short Circuit at the Connectors for the Balance Valve Solenoid

1. Remove electrical power from the ECM.

2. Fabricate a jumper wire that is long enough to create a short circuit across the solenoid connectors. Crimp connector pins to each end of the jumper wire.

3. Install the jumper wire across terminal 1 (solenoid signal) and terminal 2 (return) of the harness connector for the balance valve solenoid.

4. Restore the electrical power to the ECM.

5. Proceed to the "Diagnostic Overrides" screen on Cat ET.

6. Activate the "Engine Exhaust Manifold Bank #1 Flow Balance Valve Solenoid Override".

   Note: The ECM can only detect a short circuit condition on this circuit when the output driver is activated.

7. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

   A -6 code will be active for the solenoid.

8. Remove electrical power from the ECM.

Expected Result:

A -6 code became active while the jumper wire was installed during the test.

Results:

• OK - A -5 code was active before the jumper wire was installed. A -6 code became active after the jumper wire was installed.

  Repair: The balance valve solenoid has an open circuit in the windings of the solenoid. Replace the faulty solenoid.

  STOP

• Not OK - A -5 code was active before the jumper wires were installed. The -6 code did not become active after the jumper wires were installed. The open is in the harness wiring between the connector for the balance valve solenoid and the ECM. There may be a problem with the ECM. Proceed to Test Step 10.

Test Step 10. Check the Operation of the ECM

1. Remove electrical power from the ECM.

2. Disconnect the J2/P2 ECM connectors.

3. Fabricate two jumper wires that are long enough to create a test circuit across the ECM connector. Crimp a connector socket to one end of each of the jumper wires.

4. Install the jumper wires into terminal locations P2-4 (solenoid signal) and P2-52 (return).

5. Connect the J2/P2 connectors.

6. Check the operation of the ECM by creating an open at the ECM:

   1. Ensure that the loose ends of the jumper wires are isolated from any ground source during this portion of the test.

   2. Restore the electrical power to the ECM.

      Note: The ECM can only detect an open circuit condition on this circuit when the output driver is not activated.

   3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

      Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

      A -5 code will become active for the balance valve solenoid with the open circuit in place.

   4. Remove electrical power from the ECM.

7. Check the operation of the ECM by creating a short at the ECM:

   1. Connect the loose end of the jumper wires together.

   2. Restore the electrical power to the ECM.

   3. Proceed to the "Diagnostic Overrides" screen on Cat ET.

   4. Activate the "Engine Exhaust Manifold Bank #1 Flow Balance Valve Solenoid Override".

      Note: The ECM can only detect a short circuit condition on this circuit when the output driver is activated.

   5. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes.

      Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

      A -6 code will become active for the balance valve solenoid with the short circuit in place.

8. Remove electrical power from the ECM.

9. Return all wiring to the original configuration.

Expected Result:

A -5 code is active when the jumper wires are open. A -6 code is active when the jumper wires are short circuited.

Results:

• OK - A -5 code is active when the circuit is open. A -6 code is active when the jumper wires are shorted.

  Repair: The ECM is operating properly. The problem is in the wiring between the ECM and the balance valve solenoid. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Not OK - One of the following conditions exists: A -5 code is not active when the jumper wires are open. A -6 code is not active when the wire jumpers are shorted.

  Repair: The ECM does not detect the open circuit or the short circuit at the ECM connector. There may be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solution Network (DSN).

  STOP