C7.1 Engines For Caterpillar Built Machines Caterpillar

When the Aftertreatment Regeneration Device (ARD) requires troubleshooting, there will be multiple codes in order to assist the troubleshooting process. A "Soot Loading-High" code is not the cause of the fault. Troubleshoot one of the following associated codes in order to clear the fault that has caused the "Soot Loading-High" code:

• 3473-31 Aftertreatment #1 Failed to Ignite

• 3474-31 Aftertreatment #1 Loss of Combustion

• 3703-31 Particulate Trap Active Regeneration Inhibited Due to Inhibit Switch

• 3711-31 Particulate Trap Active Regeneration Inhibited Due to Low Exhaust Gas Temperature

• 3714-31 Particulate Trap Active Regeneration Inhibited Due to Temporary System Lockout

• 3750-31 DPF #1 Conditions Not Met for Active Regeneration

Troubleshooting the associated codes may lead to a code that is the root cause of the fault.

The following paragraph is an example of troubleshooting the engine system with "Associated Codes".

After connecting the electronic service tool to an engine, the following codes are displayed:

• A "Soot Loading - High" code (the high-level code)

• An "Insufficient Temperature to Regenerate" code (the associated code)

• A "Nozzle Not Responding" code (the code that is identified by the associated code as the cause of the fault)

This example is the result of a fouled nozzle. The ARD was unable to increase the exhaust gas temperature enough to regenerate the Diesel Particulate Filter (DPF) because the fittings or the nozzle failed. The "Soot Loading-High" code was generated because the trap was unable to regenerate. The troubleshooting procedure that would be followed in this case would be the "Nozzle Not Responding" code, which will correct the other two codes.

Engine operation must be kept to a minimum in order to minimize the amount of soot that is created. Follow the troubleshooting procedure in order to minimize the amount of engine operation.

The Electronic Control Module (ECM) maintains an estimate of the soot load in the DPF. The estimate is based on the operating conditions of the engine. If the ECM estimates that the soot load is excessive, the ECM activates the applicable code.

Table 1

Diagnostic Trouble Codes for Excessive Soot Load
J1939 Code and Description	Information that Relates to the Code
3719-16 High Diesel Particulate Filter #1 Soot Loading - Level 2	The estimated soot load is high. The ECM shuts down the engine when this code becomes active for the first time. The engine can be started and operated. Engine power is gradually derated as the soot load increases.
3719-0 High Diesel Particulate Filter #1 Soot Loading - Level 3	The estimated soot load is very high. Engine operation is limited to 30 second intervals when the electronic service tool is not communicating with the ECM.
3715-31 Diesel Particulate Filter Active Regeneration Inhibited Due to Permanent System Lockout - Level 3	The estimated soot load is very high. The engine may not operate properly. Factory passwords are required in order to clear this code.
Follow the troubleshooting procedure in order to determine the root cause of the problem.

Troubleshooting Procedure

1. Perform this test step only when a 3715-31 code is displayed. The 3715-31 code indicates that the engine has continued to run after repeated warnings and engine shutdowns.

   1. Replace the DPF. Refer to Disassembly and Assembly, "Diesel Particulate Filter - Remove" and Disassembly and Assembly, "Diesel Particulate Filter - Install" for the correct procedure.

2. Connect the electronic service tool to the diagnostic connector. Check for diagnostic codes that relate to the Clean Emissions Module (CEM). Refer to Table 2. Troubleshoot any codes that are present before continuing with this procedure.
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   Table 2

   Associated Codes
   J1939 Suspect Parameter Number (SPN)	Failure Mode Identifier (FMI)
   3703	31
   3750	31
   3711	31
   3473	31
   3474	31
   3714	31

   Troubleshoot the systems in the order that is listed above if there are diagnostic codes for more than one of the systems. Use the electronic service tool to perform a service regeneration after the successful completion of the diagnostic procedures.

   1. If there are no associated codes, proceed to Test Step 3.

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Illustration 1	g02442196
Typical view of the CEM (1) Diesel Oxidation Catalyst (DOC) (2) DPF inlet pressure sensor (3) Nozzle heater relay (4) Diesel Particulate Filter (DPF) (5) Soot antennas (6) ARD combustion head

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Illustration 2	g02232033
Measuring the current through the ARD nozzle heater (7) ARD combustion head (8) Metal part of heater wire (9) Insulated part of heater wire

3. Use the following procedure to check the ARD nozzle heater:

   1. Verify that the engine is off.

   2. Connect a suitable clamp-ammeter around the insulated part of the heater wire (9). Make sure that the jaws of the ammeter are away from the metal part of the heater wire (8) .

   3. Establish communication between the electronic service tool and the ECM. Refer to Troubleshooting, "Electronic Service Tools" for the proper procedure.

   4. Start the engine. Use the electronic service tool to activate the "ARD Nozzle Heater Test".

   5. Check that the ammeter reads at least 7 Amps for a 12 VDC system or 3.5 Amps for a 24 VDC system.

   6. Disable the "ARD Nozzle Heater Test". Stop the engine. Remove the clamp-ammeter.

   7. Disconnect the electronic service tool.

   8. If the current flow is acceptable, proceed to Test Step 4.

   9. If the current flow is not acceptable, refer to Troubleshooting, "ARD Nozzle Heater - Test".

4. Use the following procedure to test the ARD air system:

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

   2. If the ARD Air System Service Test is not successful, troubleshoot the ARD air supply and then proceed to Test Step 5.

      If the ARD Air System Service Test is successful, proceed to Test Step 5 .

5. Perform this Test Step if all of the following conditions are true:
   • The "DPF Disable" switch was not disabling the ARD.

   • The ARD fuel nozzle is operating correctly.

   • The results of the "ARD Combustion Air - Test" are acceptable.

   Proceed to Test Step 6 if a fault has been discovered and the fault has been rectified.

   1. Perform the "Cylinder Cutout Test" on the electronic service tool. If there is a fault with injection, make the necessary repairs and proceed to Test Step 6. If there is not a fault with injection, continue with this procedure.

   2. Remove the inlet section from the DPF. Inspect the inside of the inlet section and the front face of the DPF. Look for oil and for excessive soot.

      The presence of a small amount of soot is a normal condition. If the amount of soot is considered to be excessive, contact the technical communicator at the Caterpillar dealer. Continue with this procedure after guidance has been received from the technical communicator.

      If oil is found, inspect the outlet of the turbocharger. If oil is found, contact the technical communicator at the Caterpillar dealer. Continue with this procedure after guidance has been received from the technical communicator. Clean the oil from the inside of the inlet section of the DPF and the front face of the DPF. Assemble the DPF. Run the engine at 1400 rpm for 15 minutes. Then, proceed to Test Step 6.

Note: Do not use the cab switch for a stationary regeneration. The service tests provide enhanced diagnostics that are necessary for proper troubleshooting and repair.

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

   • "Service Procedures"

   • "Manual Diesel Particulate Filter Regeneration"

   Return the engine to service after a successful service regeneration.