C13 and C15 On-highway Engines Caterpillar

There are two nozzles inside the ARD combustion head. The nozzles inject pilot fuel and main fuel into the ARD for combustion. The nozzles can become plugged with carbon or with debris. The ARD purge air system forces pressurized air through the nozzles in order to clean the nozzles. The Engine Control Module (ECM) periodically tests the condition of the ARD purge air system. Table 1 lists the diagnostic trouble codes for the ARD purge air system.

System Operation Description

The ARD purge air system provides pressurized air for the Aftertreatment Regeneration Device (ARD). The pressurized air performs the following functions:

• The pressurized air minimizes the buildup of carbon on the nozzles inside the ARD combustion head.

• The pressurized air removes residual fuel from the fuel lines to the ARD.

• The pressurized air forces cleaner through the nozzles when cleaner is present in the ARD purge air system.

Illustration 1	g01420880
Schematic diagram of the ARD purge air system Components in the fuel system that relate to the ARD purge air system are shown in this schematic. Check valves (20) are not serviceable separately. (1) Fuel filter base (2) Fuel enable valve (3) Return check valve (4) Fuel manifold (5) Pilot fuel control solenoid (6) Main fuel control solenoid (7) Pilot fuel pressure sensor (8) Main fuel pressure sensor (9) Manifold for the lines to the ARD (10) Filter (11) Filter (12) ARD combustion head (13) ARD purge air pump (14) 40 micron filter (15) First check valve (16) Cleaning port (17) Purge line (18) Second check valve (if equipped) (19) filter (20) Check valves inside the ARD combustion head (21) Nozzles (22) Vehicle's fuel tank

Refer to Illustration 2 and Illustration 3. The ARD purge air system consists of the following components:

Illustration 2	g01397337
Typical view of the left side of the engine (13) ARD purge air pump (14) 40 micron filter (15) First check valve (16) Cleaning port (17) Purge line (22) 4-pin connector for the ARD purge air pump (23) This 2-pin connector is not used.

Illustration 3	g01410811
Typical manifold for the lines to the ARD combustion head (9) Manifold for the lines to the ARD combustion head (17) Purge line (18) Second check valve (if equipped)

Illustration 4	g01397242
Mechanical portion of the ARD purge air pump

ARD Purge Air Pump (13) - The ARD purge air pump receives filtered air from the vehicle's air cleaner. The pump compresses the air. The pump consists of two parts. One part of the pump contains the electrical components. The other part of the pump is the mechanical portion. The mechanical portion can be serviced separately.

Filter (14) - The 40 micron filter cleans the compressed air.

First Check Valve (15) - This check valve prevents fuel or cleaner from entering filter (14) and pump (13).

Cleaning Port (16) - The cleaning port provides a location for introducing cleaner into the ARD purge air system.

Second Check Valve (18) - This optional check valve enables the flow of purge air when there is no pilot fuel pressure. This check valve disables the flow of purge air when there is pilot fuel pressure.

System Operation

The ARD purge air pump operates after any of the following conditions occur:

• The keyswitch is turned on and 15 seconds elapse.

• The keyswitch is turned off during an active regeneration.

• An active regeneration is completed.

• A "loss of combustion" event occurs.

• The ARD fails to ignite.

The ARD purge air pump receives electrical power from the vehicle's battery. The circuit is protected by a fuse or by a circuit breaker.

The ECM sends a command signal to the ARD purge air pump. The command signal is 12 VDC. The command signal turns on the pump. The pump operates at two speeds. The operating speed is determined by software inside the pump. The sound of the pump changes as the pump operates at the different speeds. This is normal operation.

The ARD purge air pump operates for a period of time that is determined by the flash file in the ECM. The pump turns on and the pump turns off periodically. This is normal operation.

The purge process has two parts. The following information describes each part of the purge process.

Purging the Nozzles

The ECM does not energize solenoids (5) and (6) during this part of the purge process. The solenoids are closed.

Pressurized air flows from ARD purge air pump (13) through filter (14) and through check valves (15) and (18). The pressurized air flows through two nozzles in ARD combustion head (12). The pressurized air cannot flow past de-energized solenoids (5) and (6). The system pressure is approximately 280 kPa (40 psi) during this part of the purge process. The actual pressure depends on the following conditions:

• Barometric pressure

• Cleanliness of the nozzles

The ECM monitors the signals from pressure sensors (7) and (8) as the nozzles are purged. A diagnostic trouble code is activated if either pressure is outside the normal operating range.

Cleaner is introduced into cleaning port (16) in order to clean the nozzles and the check valves. The cleaner must be introduced for the following reasons:

• According to the maintenance schedule in the engine's Operation and Maintenance Manual

• There is a diagnostic trouble code for the ARD purge air system.

Purging the Fuel Lines to the ARD Combustion Head

The ECM commands solenoids (5) and (6) to completely open. This allows residual fuel to flow through the solenoids. The purge air forces residual fuel to return to fuel tank (22) via de-energized fuel enable valve (2). Return check valve (3) prevents fuel from returning to the ARD if there is a problem with the return line to the fuel tank. The pressure is approximately 40 kPa (6 psi) during this part of the purge process.

The ECM de-energizes solenoids (5) and (6) after the residual fuel has returned to the fuel tank.

The ECM monitors the signals from pressure sensors (7) and (8) as the lines are purged. A 3486-7 diagnostic code is activated if the following conditions are true:

• The pilot pressure or the main pressure is low while the nozzles are being purged.

• The pressures are not approximately equal while the lines are being purged.

These conditions indicate that one of the check valves (20) inside the ARD combustion head is stuck in the closed position.

Abnormal Purge Pressure

Certain system failures cause the purge pressure to be outside the normal operating range. Refer to Illustration 5.

Illustration 5	g01481304
Purge pressure for different system failures Refer to the troubleshooting procedure for the actual pressure values.

Note: Barometric pressure affects the normal operating range. Barometric pressure can be read on the Caterpillar Electronic Technician (ET). The parameter is in "Status Group 16".

Operation of the ARD Purge Air Pump During Engine Operation

The ARD purge air pump runs while the engine is running. This minimizes the buildup of carbon on the nozzles. The pump is turned off during active regenerations.

Illustration 6	g01454820
Electrical schematic for the ARD purge air system The pump's 2-pin connector is not used.

Override on the Caterpillar Electronic Technician (ET)

An override is available on Cat ET for activating the ARD purge air pump. Approximately 40 seconds are required for the pump to create full pressure after the override is turned on. The following list describes the sequence of operation.

• The override is enabled.

• If the pump is not operating, the pump operates at low speed for 20 seconds.

• Then, the pump begins operation at high speed.

• Approximately 20 seconds of high speed operation are required in order for the pump to build maximum pressure.

• The pump operates at high speed for four minutes. Then, the pump changes to low speed operation.

Illustrations 7 and 8 describe the activation of the override.

Illustration 7	g01396661
Access the "System Troubleshooting Settings" menu.

Illustration 8	g01396667
Change the "Aftertreatment Regeneration Device Purge Air Actuator Override" to "On".

Test Step 1. Identify the Problem

Note: A special process is required in order to clear 3486-7 and 3486-17 codes. The process is described in the last test step of this procedure. Do not clear either code until the ARD purge air system is working correctly.

1. Establish communication between Cat ET and the engine ECM. Verify that the service tool is communicating on both data links.

2. Look for the following diagnostic trouble codes:

   • 3486-7 Aftertreatment #1 Purge Air Pressure : Not Responding Properly

   • 3486-17 Aftertreatment #1 Purge Air Pressure : Low - Least Severe (1)

   • 3490-6 Aftertreatment #1 Purge Air Actuator : Current Above Normal

Expected Result:

A 3486-17 code is logged.

Results:

• A 3486-17 code is logged. - Proceed to Test Step 2.

• A 3486-7 code is logged. - Proceed to Test Step 7.

• A 3490-6 code is logged. - Proceed to Test Step 8.

Test Step 2. Check for an Electrical Problem

1. Use the override on Cat ET to turn on the pump. Wait for 20 seconds. This allows the pump to begin high speed operation.

   Note: The pump must change from low speed operation to high speed operation. You must touch the pump or you must listen to the pump in order to determine if the pump changes to high speed operation.

2. Touch the pump or listen to the pump in order to determine if the pump is running at high speed.

Expected Result:

The pump changed to high speed operation.

Results:

• The pump changed to high speed operation. - The wiring is OK. The electrical portion of the pump is OK. Proceed to Test Step 3.

• The pump did not change to high speed operation. - The wiring is OK. The electrical portion of the pump is not OK.

  Repair: Replace the entire ARD purge air pump.

  Proceed to Test Step 3 in order to continue checking the remainder of the system.

• The pump is not running. - There is an electrical problem.

  Repair: The pump requires two electrical inputs in order to run:

  • Battery voltage from the vehicle

  • A command signal from the ECM
  Refer to Illustration 6 as you check the electrical inputs:

  1. Use 7X-1710 Multimeter Probes to check for battery voltage between terminals 2 and 3 on the pump's 4-pin connector.

     If battery voltage is not present between terminals 2 and 3, check for these problems:

     • Blown fuse or tripped circuit breaker

     • Disconnected electrical connector

     • An open circuit in the vehicle's wiring harness

     • An open circuit in the engine harness

     • A problem with a socket or with a crimp in an electrical connector

     If battery voltage is present between terminals 2 and 3, continue with this procedure.

  2. Touch the pump or listen to the pump in order to determine if the pump is running. Use the override on Cat ET to turn on the pump, if necessary.

  3. Use 7X-1710 Multimeter Probes to check for 12 VDC between terminals 2 and 4 on the pump's 4-pin connector.

     If there is not 12 VDC between terminals 2 and 4, there is a wiring problem between the pump's 4-pin connector and the P2 connector. Repair the wiring. Replace parts, if necessary.

     If there is 12 VDC between terminals 2 and 4, replace the ARD purge air pump.

  Proceed to Test Step 3 in order to continue checking the remainder of the system.

Test Step 3. Inspect the Flexible Line

Illustration 9	g01409406
Typical configurations (24) Flexible line (25) Location for checking the dead head pressure of the ARD purge air pump

Inspect flexible line (24). Look for the following conditions:

• Verify that both ends of the line are securely connected.

• Check the line for signs of excessive pressure.

Expected Result:

The flexible line is OK.

Results:

• The flexible line is OK. - Proceed to Test Step 4.

• The flexible line is not OK. -

  Repair: Make the necessary repairs.

  Continue to Test Step 4 after the flexible line is repaired.

Test Step 4. Check the Dead Head Pressure of the ARD Purge Air Pump

1. Refer to Illustration 9. Disconnect the line from the outlet of the filter at location (25).

2. Connect a pressure gauge to the outlet of the filter.

3. Verify that the pump is running at high speed by touching the pump or by listening to the pump. Use the override on Cat ET to turn on the pump, if necessary.

Expected Result:

The dead head pressure is between 450 kPa (65 psi) and 650 kPa (95 psi).

Results:

• The dead head pressure is between 450 kPa (65 psi) and 650 kPa (95 psi). - The pump is working correctly. Proceed to Test Step 5.

• The dead head pressure is below 450 kPa (65 psi) or above 650 kPa (95 psi). - The mechanical portion of the pump has failed.

  Repair: Perform the following procedure:

  Show/hide table

  Illustration 10	g01397242
  Mechanical portion of the ARD purge air pump

  1. Replace the mechanical portion of the ARD purge air pump.

  2. Verify that the dead head pressure of the pump is between 450 kPa (65 psi) and 650 kPa (95 psi).

  3. Remove the pressure gauge from the outlet of the filter. Connect the line to the filter. Make sure that the connection is tight.

  Proceed to Test Step 5.

Test Step 5. Check the Dead Head Pressure After the First Check Valve

This test step determines if check valve (15) is stuck in the closed position. The pressure must be checked on the downstream side of check valve (15) and before manifold (9). Review Illustration 11 before you perform the procedure.

Illustration 11	g01410813
Locations for checking the dead head pressure after the first check valve

Check the dead head pressure at either of the following locations:

• The outlet of the first check valve

• The end of the purge line near the manifold

1. Select a location for checking the dead head pressure.

2. If you are checking the dead head pressure at the outlet of the first check valve, perform the following procedure in order to properly connect the pressure gauge:

   1. Disconnect the line from the inlet of the check valve.

   2. Remove the check valve from the tee.

   3. Connect the check valve to the end of the line.

   4. Connect the pressure gauge to the outlet of the first check valve.

3. If you are checking the dead head pressure at the end of the purge line near the manifold, perform the following procedure in order to properly connect the pressure gauge:

   1. Disconnect the purge line from the manifold.

   2. Connect the pressure gauge to the end of the purge line.

4. Verify that the pump is running at high speed by touching the pump or by listening to the pump. Use the override on Cat ET to turn on the pump, if necessary.

5. Wait for 45 seconds in order for the pump to operate at high speed. Observe the pressure on the gauge.

Expected Result:

The dead head pressure is below 450 kPa (65 psi).

Results:

• The dead head pressure is below 450 kPa (65 psi). - The first check valve is stuck in the closed position. The closed check valve is blocking the air flow to the ARD.

  Repair: Perform the following procedure:

  1. Remove the pressure gauge from the system.

  2. Replace the first check valve.

  3. Connect the lines.

  4. Determine if the engine is equipped with a second check valve (18).

  If the engine has a second check valve, proceed to Test Step 6. If the engine does not have a second check valve, proceed to Test Step 7.

Test Step 6. Check the Dead Head Pressure After the Second Check Valve

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Illustration 12	g01410712
Location of the purge line on the ARD combustion head

1. The dead head pressure can be checked at the end of the purge line near the ARD combustion head or at the manifold. Select the location that is easiest to access.
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   Illustration 13	g01410738
   Connecting a pressure gauge to the end of the purge line

2. If the ARD combustion head is easier to access, disconnect the purge line from the ARD combustion head. Connect a pressure gauge to the end of the purge line. Refer to Illustration 13.

3. If the manifold is easier to access, trace the purge line from the ARD combustion head to the manifold. Disconnect the purge line from the connector on the manifold. Connect a pressure gauge to the connector on the manifold.

4. Verify that the pump is running by touching the pump or by listening to the pump. Use the override on Cat ET to turn on the pump, if necessary.

5. Observe the pressure on the pressure gauge.

Expected Result:

The dead head pressure is below 450 kPa (65 psi).

Results:

• The dead head pressure is below 450 kPa (65 psi). - The second check valve is stuck in the closed position.

  Repair: Perform the following procedure:

  1. Replace the second check valve (18).

  2. Check the dead head pressure after the new check valve is installed. Verify that the pressure is above 450 kPa (65 psi) when the pump is running at high speed.

  Proceed to Test Step 7.

Test Step 7. Clean the Check Valves Inside the ARD Combustion Head

1. Record the barometric pressure. The parameter is in "Status Group 16" on Cat ET.

2. Set up Cat ET to view the values of the following status parameters:

   Note: The parameters are in status group "Aftertreatment Regeneration 3".

   • "ARD Pilot Fuel Pressure"

   • "ARD Fuel Pressure"

3. Clean the check valves by introducing cleaning fluid into the cleaning port. Refer to "ARD Nozzle - Clean" in the engine's Operation and Maintenance Manual for the correct procedure.

4. Verify that the pump is running at high speed by touching the pump or listening to the pump. Use the override on Cat ET to turn on the pump, if necessary. Be sure that the pump is running at high speed.

5. Record the pressure values.
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   Illustration 14	g01384472
   Trip line for a check valve that is stuck A stuck check valve can cause the purge pressure to be below trip line (B).

6. Refer to Illustration 14. Identify your barometric pressure on the chart. Compare the pressure readings to the trip line on the chart.

Expected Result:

The pilot pressure or the main pressure was below the trip line.

Results:

• No - Both pressures were above the trip line. One cleaning solved the problem. Proceed to Test Step 9.

• Yes - The pilot pressure or the main pressure was below the trip line. Cleaning the check valves did not solve the problem.

  Repair: The ARD combustion head must be replaced. Perform the following steps in order to replace the ARD combustion head:

  Note: The fuel system must be flushed and the connector filters must be replaced before installing a new ARD head.

  Note: There is a third connector filter that needs to be replaced in a system that has an ARD purge air pump. The third connector filter is also located in the manifold for the lines to the ARD head. The filter is for ARD purge air to the ARD head.

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  Illustration 15	g01731615
  Fuel lines on the ARD combustion head

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  Illustration 16	g01731617
  The connector filters are located in the manifold for the lines to the ARD head. (26) Location of the connector filters on C15 applications (27) Location of the connector filters on certain C13 applications

  1. Flush the fuel system and replace the connector filters exactly as instructed in the Special Instruction, REHS3848, "Procedure to Flush the Fuel System for the Aftertreatment Regeneration Device (ARD)". Refer to illustration 15 and illustration 16.

  2. Install a new ARD head. Ensure that all electrical connections are connected. Ensure that all fuel connections are connected. Use the correct torque on all fuel line fittings.

  3. You must check the fuel lines for leaks after the ARD combustion head and the connectors are installed. Refer to Special Instruction, REHS3412, "Inspecting the Fuel System for the Aftertreatment Regeneration Device".

  Proceed to Test Step 9.

Test Step 8. Isolate the Problem

1. Turn the keyswitch to the off position. Clear the 3490-6 diagnostic trouble code.

2. Disconnect the 4-pin connectors for the pump.

3. Turn the keyswitch to the on position. The ECM will send a command signal to the pump after a 15 second delay.

4. Look for an active 3490-6 diagnostic trouble code after the 15 second delay.

Expected Result:

A 3490-6 diagnostic trouble code becomes active.

Results:

• Yes - When the pump is disconnected, a 3490-6 diagnostic trouble code becomes active. The pump is not causing the code. There is a problem with the wiring between the 4-pin connector and the P2 connector.

  Repair: Carefully following this procedure is a good way to identify the cause of a wiring problem:

  1. Carefully inspect the wiring and the connectors. Look for these problems:

     • Wiring that has been damaged by excessive heat

     • Wiring that has been damaged by chafing

     • Moisture on electrical connectors

  2. Repair the wiring, when possible. Replace parts, if necessary. Then, clean the nozzles. Refer to "ARD Nozzle - Clean" in the engine's Operation and Maintenance Manual for the correct procedure.

  Proceed to Test Step 10.

• No - When the pump is disconnected, a 3490-6 diagnostic trouble code does not become active.

  Repair: Replace the ARD purge air pump. Then, clean the nozzles. Refer to "ARD Nozzle - Clean" in the engine's Operation and Maintenance Manual for the correct procedure.

  Proceed to Test Step 10.

Test Step 9. Clear the Diagnostic Trouble Code for the ARD Purge Air System

Clear the diagnostic trouble code after the ARD purge air system has been repaired.

1. Verify that the engine ECM has the latest version of software.

2. Start the engine. The diagnostic trouble code is only active when the engine is running.

3. Click the "Disconnect" icon on Cat ET in order to disconnect Cat ET from the engine.

4. Turn the keyswitch to the Off position. Wait for five seconds.

5. Turn the keyswitch to the On position.

6. Click the "Connect" icon on Cat ET in order to connect Cat ET to the engine. This process allows Cat ET to establish the proper security with the engine ECM.

7. Use the "Reset All" button on the "Active Events" screen in order to clear the 3486-17 or 3486-7 code.

8. Stop the engine. Then, start the engine.

9. Check the "Active Events" screen. If either code immediately returns, this entire test step must be performed again.

Expected Result:

The diagnostic trouble code is cleared.

Results:

• The diagnostic trouble code is cleared. - Proceed to Test Step 10.

Test Step 10. Perform a Stationary Regeneration

1. The ECM disables the ARD if a 3715-31 code is active. Perform the following procedure if a 3715-31 is present. If there is no 3715-31 code proceed to the next step for performing the stationary regeneration.

   Use Cat ET in order to view the following status parameters:

   Note: You may need to create a new status group in order to view these parameters.

   • "Diesel Particulate Trap #1 Differential Pressure"

   • "Diesel Particulate Trap #2 Differential Pressure" (if equipped)

   1. Start the engine and run the engine at 1400 rpm.

   2. Monitor the differential pressure for 30 seconds.

   3. Replace any DPF that exceeds 15 kPa (2.1 psi) differential pressure.

   4. Clear the 3715-31 code for any DPF that does not exceed 15 kPa (2.1 psi) differential pressure and proceed to the next step for performing the stationary regeneration.

2. 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

3. Click the "Disconnect" icon on Cat ET in order to disconnect Cat ET from the engine.

4. Turn the keyswitch to the Off position. Wait for five seconds.

5. Turn the keyswitch to the On position.

6. Click the "Connect" icon on Cat ET in order to connect Cat ET to the engine.

7. Start the engine. Allow the engine to idle for three minutes.

8. Start a stationary regeneration by selecting the following menus on Cat ET:

   • "Service"

   • "Service Procedures"

   • "Manual Diesel Particulate Filter Regeneration"

   Cat ET will display a "Waiting On Requirements" window. The ECM will automatically elevate the engine speed to 1400 rpm. If the "Waiting On Requirements" window remains displayed for more than five minutes, abort the regeneration. Then, select the menu options again in order to start the stationary regeneration.

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

   Note: The ECM tests the nozzles for plugging after the stationary regeneration is complete. Approximately ten minutes are required in order for the test to provide a result. A 3556-7 code will become active if the nozzles are plugged.

Results:

• The stationary regeneration completes successfully. - STOP

• The stationary regeneration did not complete successfully. -

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

  STOP