Home » ISX11.9 CM2250 - Service Manual » Cummins ISX11.9 CM2250 – Service Manual 011-056   Exhaust System Diagnostics

Cummins ISX11.9 CM2250 – Service Manual 011-056   Exhaust System Diagnostics

General Information

TOC

The following procedure contains troubleshooting steps and information regarding the aftertreatment system.

 
SMALL | MEDIUM | LARGE


Leaks in the exhaust system can cause exhaust odor or white smoke.

Inspect the exhaust piping for leaks, cracks, and loose connections. Refer to Procedure 010-024 in Section 10.

Tighten the exhaust clamps, if necessary. Refer to the OEM service manual for the correct torque value.

It may be necessary to perform a stationary (parked) regeneration to locate exhaust leaks. Refer to Procedure 014-013 in Section 14.

SMALL | MEDIUM | LARGE
   


The ambient temperature affects the length of time it will take to perform a stationary (parked) regeneration because the engine must work harder to increase the exhaust temperatures to the appropriate levels in cold ambient temperatures.

In cold ambient temperatures (approximately -18°C [0°F] or colder), stationary (parked) regeneration may take longer to complete. In extremely cold ambient temperatures, stationary (parked) regeneration may not complete.

In these cases, it may be necessary to warm the engine to operating temperature before starting the stationary (parked) regeneration, or to move the vehicle to a location with higher ambient temperatures.

 
SMALL | MEDIUM | LARGE
   


The vehicle manufacturer has the option of installing two switches that control aftertreatment function: the start switch and the permit switch.

The start switch (called the Diesel Particulate Filter Regeneration Start Switch in INSITE™ electronic service tool) is used to start a stationary (parked) regeneration. The vehicle manufacturer may also reference this switch as a “stationary regeneration switch,” “start switch,” or “parked regeneration switch”.

The permit switch (called the Diesel Particulate Filter Permit Switch in INSITE™ electronic service tool) is used to allow the operator to disable active regeneration, if necessary. The vehicle manufacturer may also reference this switch as an “inhibit switch,” “stop switch,” or “disable switch”.

The start switch can be hardwired to the ECM, or it can be multiplexed over J1939 multiplexing.

If the start switch is hardwired, it shares an ECM pin with the diagnostic switch. When the switch is turned ON and the engine is OFF, the ECM interprets this signal as the diagnostic switch. When the switch is turned ON and the engine is operating, the ECM interprets this signal as the start switch.

If the start switch is J1939-multiplexed, the signal for this switch is broadcast over the J1939 data link.

A J1939-multiplexed start switch signal has priority over a hardwired start switch signal. Therefore, if the start switch is enabled over J1939, the hardwired signal is ignored by the engine ECM.

The default setting for the start switch is OFF. If the start switch is enabled to INSITE™ electronic service tool, but no switch is installed (either hardwired or J1939-multiplexed), the switch status will remain OFF.

The position of the start switch can be monitored with INSITE™ electronic service tool in the Data Monitor/Logger screen.

The default setting for the permit switch is enabled.

If the permit switch is enabled with INSITE™ electronic service tool, but no switch is installed (either hardwired or J1939 multiplexed), the switch status will remain OFF.

If the vehicle is operated for an extended period of time with the permit switch OFF, fault codes for the above normal levels of aftertreatment diesel particulate filter (DPF) soot load may result (Fault Codes 1921, 1922, and 2639).

If the aftertreatment DPF soot load reaches an above normal level (Fault Code 1921, 1922, and 2639), and the permit switch is OFF, the ECM will log Fault Code 2777. The ECM will also log Fault Code 2777 if the ECM is requesting active regeneration of the aftertreatment and the permit switch is OFF.

If the permit switch is multiplexed, and therefore enabled, in the J1939 section of Features and Parameters in INSITE™ electronic service tool, it must also be enabled in the aftertreatment section of Features and Parameters in INSITE™ electronic service tool. If is is not, regeneration will be inhibited.

A J1939-multiplexed permit switch signal has priority over a hardwired permit switch signal, so if the permit switch is enabled over J1939, the hardwired signal is ignored by the engine ECM.

The position of the permit switch can be monitored with INSITE™ electronic service tool in the Data Monitor/Logger screen:

  • When the permit switch is ON, active regeneration is allowed.
  • When the permit switch is OFF, active regeneration is not allowed.
 
SMALL | MEDIUM | LARGE
   


If the wiring in the harness between the engine and aftertreatment is not correct, the engine may experience frequent DPF lamp illuminations, or stationary (parked) regenerations that do not complete.

The aftertreatment temperature sensors are connected to an aftertreatment temperature sensor interface module in order to prevent them from being connected incorrectly. However, the wiring from the ECM to the aftertreatment temperature sensor interface modules could be wired incorrectly..

To verify the OEM wiring harness, use INSITE™ electronic service tool to monitor the following parameters with the ignition key ON, but with the engine not operating.

  • Aftertreatment DOC Inlet Temperature Sensor Signal Voltage (V)
  • Aftertreatment DPF Inlet Temperature Sensor Signal Voltage (V)
  • Aftertreatment DPF Outlet Temperature Sensor Signal Voltage (V)
  • Aftertreatment SCR Catalyst Intake Temperature Sensor Signal Voltage (V)
  • Aftertreatment SCR Catalyst Outlet Temperature Sensor Signal Voltage (V).

Unplug each of the aftertreatment exhaust gas temperature sensors, one at a time.

If the voltage changes when the sensor is unplugged, the OEM wiring harness is connected to the correct sensor.

If the voltage does not change when the sensor is unplugged, check the OEM wiring harness for correct pin installation. Refer to the wiring diagram for connector pin identification and location. Repair or replace the OEM wiring harness.

SMALL | MEDIUM | LARGE
   


When performing a stationary (parked) regeneration, monitor the exhaust temperatures in the aftertreatment to determine why a stationary (parked) regeneration will not complete.

Possible causes for stationary (parked) regenerations that will not complete include:

  • Misassembled OEM wiring harness
  • A plugged aftertreatment diesel oxidation catalyst (DOC)
  • A malfunctioning turbocharger.

A normal stationary (parked) regeneration will follow the pattern shown.

  • The dashed line is for the aftertreatment DOC inlet temperature sensor.
  • The dotted line is for the aftertreatment DPF inlet temperature sensor.
  • The solid line is for the aftertreatment DPF outlet temperature sensor.

When the stationary (parked) regeneration begins (1), all three temperatures should be approximately the same, and should increase at the same rate.

The wiring to the aftertreatment temperature sensors appears to be correct in this example because they all read approximately the same temperature at the beginning of the stationary (parked) regeneration and increase at the same rate.

Aftertreatment injection begins when all three temperatures reach approximately 288°C [550°F] (2).

Once aftertreatment injection begins, the aftertreatment DOC inlet temperature may vary slightly, but will typically remain between 260 and 399°C [500 and 750°F].

The aftertreatment DPF inlet and outlet temperatures will increase to approximately 482 to 649°C [900 to 1200°F]. The temperatures may vary during the stationary (parked) regeneration as the amount of fuel injected during aftertreatment injection is changed to maintain a constant temperature.

The aftertreatment DPF inlet and outlet temperatures will remain at this temperature for the duration of the stationary (parked) regeneration.

 
SMALL | MEDIUM | LARGE
   


This graph illustrates a stationary (parked) regeneration where the inlet of the aftertreatment DOC is blocked.

  • The dashed line is for the aftertreatment DOC inlet temperature sensor.
  • The dotted line is for the aftertreatment DPF inlet temperature sensor.
  • The solid line is for the aftertreatment DPF outlet temperature sensor.

In this condition, the engine speed will increase to the stationary (parked) regeneration speed of 1000 rpm.

Raising the aftertreatment temperature to the aftertreatment injection temperature may take longer to complete than normal if the inlet to the aftertreatment DOC is plugged, restricting some of the exhaust flow.

Once aftertreatment injection begins (2), the aftertreatment DPF inlet and outlet temperatures will differ greatly due to the plugged aftertreatment DOC being unable to oxidize the injected fuel. The aftertreatment DPF has some capability to oxidize the injected fuel, but can not maintain this condition without damaging the filter material over time. It is possible that white smoke would be present from the vehicle tailpipe during this condition.

The wiring to the aftertreatment temperature sensors appears to be correct in this example because they all read approximately the same temperature at the beginning of the stationary (parked) regeneration and they increase at the same rate.

The possible cause of this condition is a plugged aftertreatment DOC. Use the following procedure to inspect the aftertreatment DOC. Refer to Procedure 011-049 in Section 11.

 
SMALL | MEDIUM | LARGE
   


This graph illustrates a stationary (parked) regeneration where the engine can not build enough heat to start aftertreatment injection.

  • The dashed line is for the aftertreatment DOC inlet temperature sensor.
  • The dotted line is for the aftertreatment DPF inlet temperature sensor.
  • The solid line is for the aftertreatment DPF outlet temperature sensor.

The engine speed will likely increase to the stationary (parked) regeneration speed of 1000 rpm, but because the aftertreatment temperatures do not increase enough to start aftertreatment injection, the stationary (parked) regeneration will not complete.

The wiring to the aftertreatment temperature sensor appears to be correct in this example because they all read approximately the same temperature for the same conditions.

Possible causes of this issue include:

  • A malfunctioning turbocharger. Use the following procedure to verify that the turbocharger sector gear has full travel. Refer to Procedure 010-134 in Section 10.
  • Low ambient temperatures. Move the vehicle to a location with higher ambient temperatures.
 
SMALL | MEDIUM | LARGE
   


This graph illustrates a stationary (parked) regeneration where the wiring to the aftertreatment temperature sensors is incorrect.

  • The dashed line is for the aftertreatment DOC inlet temperature sensor.
  • The dotted line is for the aftertreatment DPF inlet temperature sensor.
  • The solid line is for the aftertreatment DPF outlet temperature sensor.

In this condition, the engine speed will increase to the stationary (parked) regeneration speed of 1000 rpm.

Aftertreatment injection will not occur in this condition because the aftertreatment DOC inlet temperature does not reach the required temperature. Because aftertreatment injection is not occurring, the aftertreatment temperatures should not read differently.

The possible cause of this condition is an incorrectly assembled aftertreatment wiring harness. See the aftertreatment exhaust gas temperature sensor wiring section of this procedure.

 
SMALL | MEDIUM | LARGE
   


This graph illustrates a stationary (parked) regeneration where the OEM wiring to the aftertreatment DOC inlet temperature sensor and the aftertreatment DPF outlet temperature sensor are reversed.

  • The dashed line is for the aftertreatment DOC inlet temperature sensor.
  • The dotted line is for the aftertreatment DPF inlet temperature sensor.
  • The solid line is for the aftertreatment DPF outlet temperature sensor.

In this condition, the engine speed will increase to the stationary regeneration speed of 1000 rpm.

Aftertreatment injection may occur in this condition (2). However, the aftertreatment DOC inlet temperature increases after aftertreatment injection begins, while the aftertreatment DPF outlet temperature remains constant.

The possible cause of this condition is that the OEM wiring to the aftertreatment DOC inlet temperature sensor and the aftertreatment DPF outlet temperature sensor are reversed. See the aftertreatment exhaust gas temperature sensor wiring section of this procedure.

 
SMALL | MEDIUM | LARGE
   

Test

TOC

NOTE: This section of the procedure provides information for testing the DEF concentration.

 WARNING 

It is unlawful to tamper with or remove any component of the aftertreatment system. It is also unlawful to use a DEF that does not meet the specifications provided or to operate the vehicle/equipment without DEF.
 WARNING 

DEF contains urea.  Do not get the substance in your eyes. In case of contact, immediately flush eyes with large amounts of water for a minimum of 15 minutes. Do not swallow. In the event the DEF is ingested, contact a physician immediately. Reference the Materials Safety Data Sheet (MSDS) for additional information.
 CAUTION 

Never add water or any other fluid besides what is specified to the DEF tank.  The aftertreatment system may be damaged.

The correct concentration of DEF is critical to the engine and aftertreatment system for correct performance.

Cummins Inc. is not responsible for malfunctions or damage resulting from what Cummins Inc. determines to be abuse or neglect. This includes, but is not limited to: operation without correctly specified DEF, lack of maintenance of the aftertreatment system, improper storage or shutdown practices, or unauthorized modifications of the engine and aftertreatment system. Cummins Inc. is also not responsible for malfunctions caused by incorrect DEF, water, dirt, or other contaminants in the DEF. Use the Cummins® DEF refractometer, Part Number 4919554, to test the concentration of the DEF.  Follow the instructions provided with the service tool.

The concentration of the DEF must be 32.5 ± 0.7 percent.

If the DEF concentration does not meet this specification, drain the DEF tank, flush the tank with distilled water, and fill the tank with new and/or known good DEF. Check the DEF concentration.

Concentration of the DEF should be checked when:

  • The vehicle has been stored for an extended period of time.
  • It is suspected that water has been added to the DEF tank.
 
SMALL | MEDIUM | LARGE
   

Contamination/Incorrect Fluid

TOC

DEF can become contaminated by the following situations:

  • If equipped, the aftertreatment DEF tank coolant heating system malfunctions, allowing coolant to mix with the DEF.
  • The aftertreatment DEF tank cap is missing or damaged, or the tank vent malfunctions.
  • The aftertreatment DEF tank is filled with the incorrect fluid.

In the event that the DEF becomes contaminated, inspect the DEF to determine the most likely source.

Obtain a sample from the DEF tank and pour the sample into an appropriate container.  Make sure to get a sample from the highest fluid level.

 
SMALL | MEDIUM | LARGE
   


Petroleum based liquids, such as, but not limited to:

  • Diesel fuel
  • Hydraulic fluid
  • Brake fluid.

Because DEF is largely composed of water, petroleum-based liquids will separate from the DEF and rise to the top. Look for separation of the fluids, as well as characteristic smells.

If the DEF is contaminated, follow the steps detailed later in this procedure.

 
SMALL | MEDIUM | LARGE
   


Non-petroleum based liquids, such as, but not limited to:

  • Water
  • Coolant
  • Windshield washer fluid.

If water has been added, the DEF will remain clear.  As a result, the DEF will become diluted, reducing the concentration level.

NOTE: If only water has been added to the DEF tank, drain the DEF tank, flush with distilled water, and fill the tank with new and/or known good DEF.  Check the DEF concentration after completing the refill. Follow the instructions in the Test section of this procedure.

For other non-petroleum based liquids that may have been added to the DEF, typically those fluids have coloring and will mix with DEF.  If the DEF has a color tint to it, look for other fluids used on the vehicle that may match, such as coolant or windshield washer fluid. 

If the DEF is contaminated, follow the steps detailed later in this procedure

 
SMALL | MEDIUM | LARGE
   


NOTE: Use INSITE™ electronic service tool to view and troubleshoot any fault codes that occur during the following steps. Use the ISB6.7 CM2250, ISC8.3 and ISL9 CM2250, and ISX15 CM2250 Fault Code Troubleshooting Manual, Bulletin 4022225.

If the DEF has been contaminated, remove the aftertreatment DEF dosing unit filter. Refer to Procedure 011-060 in Section 11.  Inspect the filter for signs that the contaminated fluid went through the dosing system.

If the contaminated fluid did not go through the dosing system, drain the DEF tank and flush with distilled water. Replace the DEF in the tank filter. Refer to the OEM service manual for specific information on servicing the DEF tank. 

After the DEF tank has been cleaned, fill the tank with new and/or known good DEF. Check the DEF concentration after completing the refill. Follow the instructions in the Test section of this procedure.

 
SMALL | MEDIUM | LARGE
   


NOTE: Any discarded contaminated fluids and/or parts must be disposed of according to local area ordinances.

If the contaminated fluid did go through the dosing system:

  1. Drain the DEF tank, flush with distilled water, and replace the DEF in the tank filter. Refer to the OEM service manual for specific information on servicing the DEF tank.
  2. Replace the aftertreatment DEF dosing unit filter. Refer to Procedure 011-060 in Section 11.
  3. Remove all of the aftertreatment DEF lines and flush with distilled water.  Refer to the OEM service manual on the handling of contaminants in the aftertreatment DEF lines. Install the aftertreatment DEF lines.
  4. Fill the aftertreatment DEF tank with distilled water.
  5. Perform INSITE™ electronic service tool DEF Doser Pump Override Test. Repeat the test until the distilled water runs clear.
  6. Drain the distilled water from the DEF tank and refill with new and/or known good DEF.  Check the DEF concentration. Follow the instructions in the Test section of this procedure.
  7. Replace the aftertreatment DEF dosing unit filter again. Refer to Procedure 011-060 in Section 11.
  8. Perform the INSITE™ electronic service tool DEF Doser Pump Override Test.  Test the performance and spray pattern of the aftertreatment DEF dosing valve.
  9. Perform a stationary regeneration. Refer to Procedure 014-013 in Section 14.
  10. Road test the vehicle for 30 minutes to verify system operation.
 
SMALL | MEDIUM | LARGE
Last Modified:  05-Jan-2011