CM850 Electronic Control System – 019-440   Aftertreatment Diesel Exhaust Fluid Dosing Unit

General Information

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 WARNING 

The diesel exhaust fluid contains urea. Do not get the substance in your eyes. In case of contact, immediately flood eyes with large amounts of water for a minimum of 15 minutes. Avoid prolonged contact with skin. In case of contact, immediately wash skin with soap and water. Do not swallow internally. In the event the catalyst reagent is ingested, contact a physician immediately. Refer to the Material Safety Data Sheet (MSDS) for additional information.
 WARNING 

The air solenoid is hot to the touch after initial shutdown. Use eye protection, gloves and appropriate personal protective equipment.

The diesel exhaust fluid dosing unit is used to administer the correct amount of diesel exhaust fluid for the aftertreatment system.

The diesel exhaust fluid dosing unit receives commands from the engine ECM via the Cummins® data link. Based on various operating conditions, the engine ECM will command the diesel exhaust fluid dosing unit to administer the diesel exhaust fluid.

NOTE: The diesel exhaust fluid dosing unit is not serviceable. Do not open the case.

NOTE: The nozzle supply hose must be made from PTFE (Polytetraflouroethylene).

 
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Initial Check

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Locate the diesel exhaust fluid dosing unit on the vehicle.

The diesel exhaust fluid dosing unit dataplate is located either on the top, or on the side of the unit, as illustrated (1).

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Check the pipework going to and returning from the diesel exhaust fluid dosing unit for any signs of a leak.

Diesel exhaust fluid leaks will leave a white deposit around the fittings.

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Preparatory Steps

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 WARNING 

Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.
 WARNING 

Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.
  • Disconnect the batteries. Refer to the OEM service manual.
  • Release the pressure in all vehicle air tanks. Refer to the OEM service manual.

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Remove

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The diesel exhaust fluid dosing unit is secured to the chassis by four mounting bolts. Depending on the installation, it can be easier to remove the pipework and connectors either before or after the diesel exhaust fluid dosing unit is removed from its mounting bracket.

The diesel exhaust fluid dosing unit must be wiped with a clean damp cloth and/or a wash bottle with mild detergent. This will remove any contamination and reduce the risk of debris entering the diesel exhaust fluid dosing unit.

NOTE: Do not jet wash or steam clean this unit.

Disconnect the electrical connections and pipework that is attached to the diesel exhaust fluid dosing unit.

  1. Compressed air supply
  2. Air solenoid connector (2 pin)
  3. 37-pin ITT Cannon™ connector
  4. Diesel exhaust fluid supply to after treatment nozzle (PTFE line)
  5. Diesel exhaust fluid supply to pump
  6. Diesel exhaust fluid return

Lines 4, 5 and 6 have quick-fit connections.

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 CAUTION 

Be sure the vehicle air supply to the dosing unit is either drained down or isolated before removing air supply line.

Air Connector

  • A quick release fitting is also used for the air connection at the top of the diesel exhaust fluid dosing unit. To release this fitting, apply equal pressure to both sides of the release collar and pull the pipe from the fitting.

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Diesel Exhaust Fluid Dosing Unit Pipe Fittings

  • The pipework is connected to the front of the diesel exhaust fluid dosing unit by quick release fittings. To remove the fittings, press either side the fitting, as shown in the illustration.

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 CAUTION 

Some OEMs use fittings of different sizes to avoid confusion. However, some OEMs use the same connections on the diesel exhaust fluid supply and diesel exhaust fluid return. Be sure the lines are connected to the correct location on the diesel exhaust fluid dosing unit.
 CAUTION 

If these fittings need to be replaced, and they are of different sizes, be sure they are fitted to the correct location on the front of the diesel exhaust fluid dosing unit.

The fittings are three different sizes.

There is an o-ring on the rear of each of these fittings.

Torque Value:  15  n.m  [133 in-lb]

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 WARNING 

The diesel exhaust fluid contains urea. Do not get the substance in your eyes. In case of contact, immediately flood eyes with large amounts of water for a minimum of 15 minutes. Avoid prolonged contact with skin. In case of contact, immediately wash skin with soap and water. Do not swallow internally. In the event the diesel exhaust fluid is ingested, contact a physician immediately. Refer to the Material Safety Data Sheet (MSDS) for more information.

Remove the four mounting bolts (1-4) from each corner of the diesel exhaust fluid dosing unit.

The diesel exhaust fluid dosing unit must be wiped with a clean damp cloth and/or a wash bottle with mild detergent. This will remove any contamination and reduce the risk of debris entering the diesel exhaust fluid dosing unit.

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Clean and Inspect for Reuse

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NOTE: This unit is not serviceable. Do not open the case. Return the unit to a Cummins® Authorized Repair Location.

Inspect the outside of the unit. If there are any cracks or damage to the mounting flanges, the exterior case or the electrical connectors, replace the diesel exhaust fluid dosing unit.

Check all connections, lines, and fittings for any signs of leaks or damage.

Repair or replace the connections as necessary.

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Test

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 WARNING 

The diesel exhaust fluid contains urea. Do not get the substance in your eyes. In case of contact, immediately flood eyes with large amounts of water for a minimum of 15 minutes. Avoid prolonged contact with skin. In case of contact, immediately wash skin with soap and water. Do not swallow internally. In the event the diesel exhaust fluid is ingested, contact a physician immediately. Refer to the Material Safety Data Sheet (MSDS) for more information.
 WARNING 

Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Diesel Exhaust Fluid Dosing Unit Override Test

The purpose of this test is to run the diesel exhaust fluid dosing pump through a dosing cycle and check for a specific amount of diesel exhaust fluid to be delivered in a specified time.

The Diesel Exhaust Fluid Dosing Unit Override Test is a fully automated test. There are three main parts to the SCR aftertreatment cycle.

  1. Priming
  2. Dosing
  3. Purging.
 
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 CAUTION 

The diesel exhaust fluid injection nozzle must be removed from the exhaust system before starting the test. Failure to do so can result in excessive ammonia emissions on subsequent startup or damage to the catalyst.

Remove the aftertreatment nozzle from the exhaust system.

The aftertreatment nozzle mounting hole in the exhaust system must be capped to eliminate exhaust leaks.

Place the nozzle in a measured container with a capacity of at least 200 militer [6.8 fl oz].

Make sure the top of the container is covered to keep any diesel exhaust fluid from spraying out of the container and affecting the test result.

NOTE: A properly sized cup plug can be inserted under the aftertreatment nozzle retaining nut and hand-tightened to block exhaust leaks during the test.

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This test must only be run with the vehicle stationary, in neutral, and the engine at idle.

Use INSITE™ electronic service tool to perform the Diesel Exhaust Fluid Dosing Unit Override Test.

Measure the amount of diesel exhaust fluid injected into the container.

Override Test Diesel Exhaust Fluid Injection Volume (Old 10 Minute Test)

ml fl-oz
900 MIN 30
1100 MAX 37

Override Test Diesel Exhaust Fluid Injection Volume (New 6 Minute Test)

ml fl-oz
50 MIN 1.69
150 MAX 5.07

NOTE: If the test lasts for 6 minutes, use the “New 6 Minute Test” specification. If the test lasts for 10 minutes, use the “Old 10 Minute Test” specification.

NOTE: If the New 6 Minute Test is used, check the INCAL™ DVD History Sheet to see if an update is available for your ECM code. The update will be labeled as “New DOT Test Specification to 100 ml in 6 Minutes”.

The expected amount is 100 ml [3.38 fl oz] in 6 minutes, within the above tolerance. If the amount of diesel exhaust fluid is not within specification:

  • Check the air supply to the diesel exhaust fluid dosing unit for blockages or restrictions.
  • Check to be sure the diesel exhaust fluid dosing unit is priming properly. Remove the diesel exhaust fluid lines from the diesel exhaust fluid dosing unit to check for blockages or restrictions.
  • Check the inlet connector with integral strainer for blockage, if applicable.
  • Perform the test again. If the amount of diesel exhaust fluid is not within specification, replace the diesel exhaust fluid dosing pump.

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Install

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NOTE: Make sure the new unit is kept free from any contamination during installation to the vehicle.

Install the electrical connections and pipework that is attached to the diesel exhaust fluid dosing unit.

  1. Compressed air supply
  2. Air solenoid connector (2 pin)
  3. 37-pin ITT Cannon™ connector
  4. Diesel exhaust fluid supply to aftertreatment nozzle
  5. Diesel exhaust fluid supply to pump
  6. Diesel exhaust fluid return

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Remove the push fit fittings from the damaged diesel exhaust fluid dosing unit and install the fittings to the replacement diesel exhaust fluid dosing unit, if required.

Torque Value:  15  n.m  [133 in-lb]

The three hoses, diesel exhaust fluid supply to nozzle, diesel exhaust fluid supply to pump, and diesel exhaust fluid return, are all quick connections.

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 WARNING 

The air solenoid is hot to the touch. Use eye protection, gloves and appropriate personal protective equipment.

Connect the two electrical connections, the air solenoid and the 37-pin connector. These are a push and twist type fit connectors.

Twist these connectors until a click is felt.

Connect the air supply line to the diesel exhaust fluid dosing unit.

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Insert the blanks from the replacement diesel exhaust fluid dosing unit or blank the fittings if possible. Install them on the damaged diesel exhaust fluid dosing unit.

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The diesel exhaust fluid dosing unit is bolted to the chassis by four bolts (1-4), one in each corner of the diesel exhaust fluid dosing unit. Attach the diesel exhaust fluid dosing unit to the OEM mounting bracket. Refer to the OEM service manual.

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Finishing Steps

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 WARNING 

Batteries can emit explosive gases. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the negative (-) battery cable first and attach the negative (-) battery cable last.
  • Connect the batteries. Refer to the OEM service manual.
  • Start and operate the engine to build up air pressure.
  • Check for air or diesel exhaust fluid leaks.
  • Check for active fault codes.

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Last Modified:  16-Dec-2009