Emission Reduction Fluid Injector Quantity Test

EMISSION REDUCTION FLUID INJECTOR QUANTITY TEST
(Vehicles With VIN L, RPO LGH Only)

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.

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.

Diagnostic Aids

Emission Reduction Fluid Injector Cleaning Procedure
* Use a clean rag/towel that is non-abrasive and dampen with water.
* Wipe the injector nozzle and cone area to remove DEF and soot deposits.
Or

Note: The water should only cover the injector nozzle and cone area.

* Soak the injector nozzle in water to soften or dissolve the DEF crystals.

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

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)

Scan Tool Reference

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

* J 35616 - GM-Approved Terminal Test Kit
* J 39021 - Fuel Injector Coil and Balance Tester
* J 45873 - Fuel Return Volume Test Kit

Circuit/System Testing

Note: Do not perform this diagnostic procedure unless you were sent here from another diagnostic procedure.

1. Remove the Q61 emission reduction fluid injector from the exhaust leaving the reductant line connected.
2. Inspect the Q61 emission reduction fluid injector nozzle and cone area for restrictions or for being plug. There should be no restrictions.

• If a condition is found, clean the Q61 emission reduction fluid injector nozzle and cone area. Refer to Diagnostic Aids for cleaning procedure.

3. Disconnect the harness connector at the Q61 emission reduction fluid injector.
4. Connect the J 39021 to the Q61 emission reduction fluid injector using jumper wires and terminals from the J 35616.
5. Set the amperage supply selector switch on the J 39021 to the Coil Test 2.5 AMP position.
6. Command the Reductant System Leak Test ON with a scan tool. Allow the pressure to build for 30 s.
7. Command the J 39021 ON. Observe the injector spray pattern. There should be 3 individual streams and atomization or mist of DEF should be observed.

• If the function does not perform as specified, inspect the reduction fluid injector lines for restrictions or for being plugged. If the reduction fluid injector lines test normal, replace the Q61 emission reduction fluid injector.

8. Position the Q61 emission reduction fluid injector nozzle towards one of the graduated scale container from the J 45873.
9. Command the Reductant System Leak Test ON with a scan tool. Allow the pressure to build for 30 s.
10. Command the J 39021 ON 4 times waiting for pressure to build-up greater than 460 kPa (67 psi) between each command. The injector should flow greater than 10 ml after 4 commands.

• If less than the specified value, test the Q61 emission reduction fluid injector and supply line for damage or restrictions. If the lines test normal, replace the Q61 emission reduction fluid injector.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Emission Reduction Fluid Injector Replacement (Service and Repair)
* Perform the scan tool Diesel Particulate Filter (DPF) Regeneration Enable (Diesel Particulate Filter (DPF) Regeneration Enable) procedure if the scan tool DPF Soot Mass is less than 30 g. If the scan tool DPF Soot Mass is greater than 30 g, perform the Diesel Particulate Filter (DPF) Service Regeneration (Diesel Particulate Filter (DPF) Service Regeneration) procedure.