Cummins ISX11.9 CM2250 – Service Manual 019-440   Aftertreatment Diesel Exhaust Fluid Dosing Unit

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

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

NOTE: The dosing control unit is not serviceable. Do not open the case.

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

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

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

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.

Locate the dosing control unit on the vehicle.

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

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

The front of the dosing unit and line connectors must be cleaned using a clean damp cloth and warm water with a mild detergent. Use a clean damp cloth to remove any contamination and reduce the risk of contamination entering the dosing control unit.

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

Disconnect the electrical connections and pipework that is attached to the dosing control unit.

1. Compressed air supply
2. Air solenoid connector (2 pin)
3. 37-pin ITT Canon™ 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.

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

Remove the air connector.

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

Remove the dosing control unit pipe fittings.

The pipework is connected to the front of the dosing control unit by quick release fittings. To remove the fittings, press either side the fittings, as illustrated in the diagram.

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 dosing control 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 dosing control unit.

The fittings are three different sizes.

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

See the Install section for fitting torque value.

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 more information.

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

Do not immerse the unit in any kind of wash.

Use only a clean damp cloth to wipe down the unit.

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 other damage to mounting flanges, the exterior case, or the electrical connectors, replace the dosing control unit.

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

Repair or replace connections as necessary.

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 more information.

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

The purpose of the Diesel Exhaust Fluid Doser Pump Override Test is to run the diesel exhaust fluid dosing unit through a dosing cycle and check for a specific amount of diesel exhaust fluid to be delivered in aspecified time.

The Diesel Exhaust Fluid Doser Pump Override Test is a fully automated test. There are three main parts to the Selective Catalytic Reduction (SCR) diesel exhaust fluid dosing cycle.

1. Priming
2. Dosing
3. Purging.

CAUTION  The urea 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.

Warm the aftertreatment nozzle in the exhaust system before removing and running this test. Operate the engine at high idle for 2 minutes with the aftertreatment nozzle still installed. Then remove the urea injection nozzle from the exhaust system. Refer to Procedure 011-042 in Section 11.

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 milliters [6.8 fl oz].

Cover the top of the container to limit any excess of the diesel exhaust fluid spraying out of the container.

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.

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 Doser Pump Override Test.

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

Override Test Urea Injection Volume

The expected amount of diesel exhaust fluid is 100 ml [3.4 fl oz] in 6 minutes within the above tolerance.If the amount of urea is not within specification.

• Check the air supply to the dosing control unit for blockages or restrictions.
• Check to be sure the dosing control unit is priming properly. Remove the catalyst solution lines from the dosing control unit to check for blockages or restrictions.
• Perform the test again. If the amount of urea is not within specification, replace the pump.

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 dosing control unit.

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

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

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

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 push-and-twist type fit connectors.

Twist these connectors until a click is felt.

Connect the air supply line to the dosing control unit.

Insert the blanks from the replacement dosing control unit or blank the fittings if possible. Install them to the damaged dosing control unit.

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

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 catalyst solution leaks.
• Check for active fault codes.