C7.1 Industrial Engine and Generator Set Caterpillar

This procedure covers the following diagnostic code:

System Operation

The combustion air system routes pressurized air from the outlet of the high-pressure turbocharger to the ARD. The combustion air is mixed with fuel inside the ARD combustion head. The air/fuel mixture is ignited and the air/fuel mixture is burned in order to increase the temperature of the exhaust gas. The high temperature exhaust gas burns off the soot in the Diesel Particulate Filter (DPF). This process is known as DPF regeneration.

The ECM sends a pulse width modulated signal to the combustion air valve. The actuator in the combustion air valve regulates the combustion air to the ARD combustion head.

The ECM also sends pulse width modulated signals to the pilot fuel control valve and the main fuel control valve. The fuel control valves regulate the amount of fuel that is injected into the ARD combustion head.

If the amount of fuel or air that enters the ARD combustion head is incorrect, combustion may not occur.

Test Step 1. Check for Associated Diagnostic Trouble Codes

1. Establish communication between the electronic service tool and the engine ECM.

2. Download the following items before performing any troubleshooting or clearing any diagnostic codes:
   • Warranty Report

   • Aftertreatment Regeneration Trigger History

   • Product Status Report with Histograms

3. Use the electronic service tool to check for active diagnostic codes.

4. Table 2 lists the diagnostic trouble codes that are associated with "3474-31 Loss Of Combustion" code. Determine if any of the codes in Table 2 are present.

Results:

• An associated diagnostic trouble code is not present. - Proceed to Test Step 2.

• An associated diagnostic trouble code is present. -

  Repair: Refer to Troubleshooting, "Diagnostic Trouble Codes" in order to troubleshoot the associated diagnostic code.

  STOP

Test Step 2. Check the Current Flow Through the Heater

1. Verify that the engine is off. Check the current flow through the heater. Refer to Systems Operation/Testing and Adjusting, "ARD Nozzle Current - Test" for the correct procedure.

Expected Result:

The current flow is above 7.0 Amps for a 12 VDC system.

The current flow is above 3.5 Amps for a 24 VDC system.

Results:

• The current flow is above the expected amount for the appropriate system voltage . - The current flow is OK. Proceed to Test Step 3.

• The current flow is below the expected amount for the appropriate system voltage . - The current flow is low.

  Repair: Determine the cause of the low current flow. Refer to Troubleshooting, "ARD Nozzle Heater - Test".

  STOP

Test Step 3. Perform a Service Regeneration

Note: This test must be performed through the electronic service tool. The electronic service tool enhances the diagnostics during the service test.

1. If the following codes are active, clear the codes. The ARD will not light if the codes are active.
   • 3703-31 Diesel Particulate Filter Active Regeneration Inhibited Due to Inhibit Switch

   • 3530-31 Aftertreatment #1 Regeneration Manually Disabled

2. Click the "Disconnect" icon on the electronic service tool in order to disconnect the electronic service tool from the engine.

3. Turn the keyswitch to the OFF position. Wait for 5 seconds.

4. Turn the keyswitch to the ON position.

5. Click the "Connect" icon on the electronic service tool in order to connect the electronic service tool to the engine.

6. Start the engine. Allow the engine to idle for 3 minutes.

7. Start a service regeneration by selecting the following menus on the electronic service tool:
   • "Service"

   • "Service Procedures"

   • "Manual Diesel Particulate Filter Regeneration"

   The electronic service tool will display a "Waiting On Requirements" window. The ECM will automatically elevate the engine speed.

   The duration of the service regeneration depends on the soot load in the DPF. The ECM will automatically return the engine speed to low idle after the service regeneration is complete.

   Note: The ECM tests the nozzle for plugging after the service regeneration is complete. An "Aftertreatment Fuel Injector #1 : Not Responding Properly" code will become active if the nozzle is plugged.

Expected Result:

The service regeneration has been successfully completed.

Results:

• The service regeneration completes successfully. - STOP

• The service regeneration did not complete successfully. -

  Repair: Check the list of active diagnostic codes. Troubleshoot the code that applies to the failed regeneration.

  Refer to Test Step 1 for associated codes.

• The service regeneration did not complete successfully and there are no associated codes. - Proceed to Test Step 4.

Test Step 4. Perform an ARD Air System Service Test

Use the electronic service tool to perform the ARD Air System Service Test.

Expected Result:

The ARD Air System Service Test completes successfully.

Results:

• The test completed successfully and did not have any associated codes. - Proceed to Test Step 5.

• The ARD Air System Service Test did not complete successfully. Also, there are associated diagnostic trouble codes. -

  Repair: Refer to Troubleshooting, "Diagnostic Trouble Codes" in order to diagnose the associated codes.

  STOP

Test Step 5. Clean the Flame Detection Temperature Sensor

Illustration 1	g02231653
(1) Flame detection temperature sensor

1. Remove the flame detection temperature sensor.

2. Clean the flame detection temperature sensor. Use a nonmetallic cleaning pad to clean the sensor.

3. Install the flame detection temperature sensor.

4. Perform a service regeneration.

Results:

• The service regeneration completed successfully. -

  Repair: Return to service.

  STOP

• The service regeneration did not complete successfully. -

  Repair: Replace the ARD head. Refer to Disassembly and Assembly, "Combustion Head Group (ARD) - Remove and Install".

  Proceed to Test Step 6.

Test Step 6. Perform an ARD Ignition Test

Show/hide table

The ignition system may cause an electrical shock hazard, which may cause personal injury or death. Avoid contacting the ignition system components and the ignition system wiring during operation.

1. Perform the ARD ignition test. Check for air leaks and fuel leaks as the test is being performed.

   Note: The ARD Ignition Test cannot be performed if the DPF soot loading is above 80%. When the DPF soot loading is above 80%, use the electronic service tool to perform a Manual DPF Regeneration.

2. Repair any leaks.

Results:

• The ARD ignition test was successful. - Proceed to Test Step 3.

• The ARD ignition test was not successful. -

  Repair: Refer to Troubleshooting, "Diagnostic Trouble Codes" in order to troubleshoot the logged diagnostic code.

  STOP