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P2049




DTC P1048, P1049, or P2047-P2049

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptors
DTC P1048
- Reductant Injector High Control Circuit Low Voltage

DTC P1049
- Reductant Injector High Control Circuit High Voltage

DTC P2047
- Reductant Injector Control Circuit

DTC P2048
- Reductant Injector Control Circuit Low Voltage

DTC P2049
- Reductant Injector Control Circuit High Voltage

Diagnostic Fault Information





Circuit/System Description

The selective catalytic reduction (SCR) system reduces oxides of nitrogen (NOx) emissions by injecting a metered amount of diesel exhaust fluid (DEF) or reductant into the exhaust gas stream entering the SCR catalyst. Within the SCR catalyst, the DEF reacts with the NOx to form nitrogen, carbon dioxide, and water vapor. Upstream and downstream NOx sensors provide the engine control module (ECM) with engine-out and tailpipe-out NOx levels. The ECM varies the amount of DEF added by varying the reductant injector duty-cycle in response to changes in engine-out NOx levels.

The ECM supplies voltage to the reductant injector on the injector high control circuit. The ECM turns ON the reductant injector by grounding the low control circuit of the injector.

Conditions for Running the DTCs

* The engine is running.
* The battery voltage is greater than 11 V.
* The ECM is commanding the reductant injector duty cycle greater than 0 %.
* The Reductant Injection Inhibit Reason displays None.
* The DTCs run continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 5 s.

Action Taken When the DTC Sets

DTCs P1048, P1049, P2047, P2048, and P2049 are Type B DTCs.

The ECM inhibits the reductant system when DTC P1048, P1049, P2048, or P2049 is set.

Conditions for Clearing the DTC

DTCs P1048, P1049, P2047, P2048, and P2049 are Type B DTCs.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

* Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Level) (Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Level)) Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Quality) (Diesel Exhaust Fluid (DEF) Warning Strategy (DEF Quality)) Diesel Exhaust Fluid (DEF) Warning Strategy (Anti-Tampering) (Diesel Exhaust Fluid (DEF) Warning Strategy (Anti-Tampering))
* Exhaust Aftertreatment System Description (Emission Control Systems)

Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

J 34730-2C Injector Test Lamp

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. DTC P1043, P1044, P204B, P204C, P204D, P208A, P208B, P208C, or P208D should not be set.

• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for further diagnosis.

2. Observe the scan tool Reductant Inj Control Circuit Status parameter. The parameter should display OK or Not Run.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the Q61 emission reduction fluid injector.
2. Ignition ON, test for B+ between DEF dosing valve high control circuit terminal 1 and ground.

• If less than the specified range, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

3. Test for 2.5-4.5 V between the DEF dosing valve low control circuit terminal 2 and ground.

• If less than the specified range, test the low control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
• If greater than the specified range, test the low control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

4. Connect a J 34730-2C between the DEF dosing valve high control circuit terminal 1 and DEF dosing valve low control circuit terminal 2.

Note: It may take several seconds for the test lamp to illuminate.

5. Command the Reductant Injector to 80 percent with a scan tool. The test lamp should illuminate or flash when commanded to 80 percent.

• If the test lamp does not illuminate or flash, replace the K20 ECM.

6. If all circuits test normal, test or replace the Q61 emission reduction fluid injector.

Component Testing

1. Ignition OFF, disconnect the harness connector at the Q61 emission reduction fluid injector.
2. Test for 10-14 ohm between the DEF dosing valve high control circuit terminal 1 and the DEF dosing valve low control circuit terminal 2 of the Q61 emission reduction fluid injector.

• If not within the specified range, replace the Q61 emission reduction fluid injector.

3. Test for infinite resistance between each terminal and the Q61 emission reduction fluid injector housing.

• If not the specified value, replace the Q61 emission reduction fluid injector.

Repair Instructions

* Emission Reduction Fluid Injector Replacement (Service and Repair)
* Perform the scan tool Reductant Injector Reset procedure after replacing the emission reduction fluid injector.
* Control Module References (Programming and Relearning) for engine control module replacement, programming, and setup

Repair Verification

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes.

Warning

Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

5. Engine idling at operating temperature. Accelerate at part throttle to 32-48 km/h (20-30 mph) for up to 5 minutes or until the DEF lamp turns OFF. The DEF lamp should turn OFF.

• If the DEF lamp does not turn OFF, a condition with the system still exists.

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