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Tahoe / Yukon Service Manual

DTC P1048, P1049, or P2047-P2049

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5501075 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P1048 Reductant Injector High Control Circuit Low DTC P1049 Reductant Injector High Control Circuit High DTC P2047 Reductant Injector Control Circuit DTC P2048 Reductant Injector Control Circuit Low DTC P2049 Reductant Injector Control Circuit High Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Control Terminal 2 P1048 P2047 P1049 —
Control Terminal 1 P2048 P2047 P2049 —

Circuit/System Description For an overview of the component/system, refer to: Exhaust Aftertreatment System Description

Circuit Description
Control — Terminal 1 The output circuit is switched to ground to activate the component.
Control — Terminal 2 The output circuit is switched to 12 V to activate the component.
Component Description
K20 Engine Control Module The reductant injector is used to dose and atomize the reductant into the exhaust system. The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to
© 2023 General Meontsourrse. oApllt irmigahl tesn rgeisneer vpeedr.formance. The control
Component Description
module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.
Q61 Reductant Injector The reductant injector is used to dose and atomize the reductant into the exhaust system.

Conditions for Running the DTC Ignition = On or Engine = Running Ignition Voltage = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 6 s Conditions for Setting the DTC P1048, P2048 Control Circuit = Short to Ground P1049, P2049 Control Circuit = Short to Voltage P2047 Control Circuit = Open Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC Reductant Injector = Off E52 Reductant Line Heater / E53 Reductant Tank Heater = Off Reductant System = Standby Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Special Tools EL-35616 GM-Approved Terminal Test Kit Equivalent regional tools: Special Tools Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify the scan tool parameter: Reductant Injector Control Circuit High Test Status = Not Run or Okay Reductant Injector Control Circuit Low Test Status = Not Run or Okay Reductant Injector Control Circuit Open Test Status = Not Run or Okay ⇒ If not the specified state Refer to: Circuit/System Testing ⇓ If the specified state
  3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC is not set
  4. All OK. Circuit/System Testing
  5. Ignition/Vehicle » Off
  6. Disconnect the electrical connector: Q61 Reductant Injector
  7. Ignition » On / Vehicle » In Service Mode
  8. Test for 2 to 3 V between the test points: Control circuit terminal 2 & Ground ⇒ If less than 2 V 4.1. Ignition/Vehicle » Off 4.2. Disconnect the electrical connector: X2 @ K20 Engine Control Module 4.3. Test for less than 2 Ω between the test points: Control circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇓ If less than 2 Ω 4.4. Test for infinite resistance between the test points: Control circuit terminal 2 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇒ If infinite resistance » Replace the component: K20 Engine Control Module 4.1. Ignition/Vehicle » Off 4.2. Disconnect the electrical connector: X2 @ K20 Engine Control Module 4.3. Ignition » On / Vehicle » In Service Mode 4.4. Test for less than 1 V between the test points: Control circuit terminal 2 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K20 Engine Control Module ⇒ If between 2 and 3 V
  9. Ignition/Vehicle » Off
  10. Connect a test lamp between the test points: Control circuit terminal 1 & Control circuit terminal 2 @ Component harness
  11. Ignition » On / Vehicle » In Service Mode
  12. Perform the scan tool control function: Reductant Injector » On Verify the test lamp flashes ⇒ If the test lamp is always Off 8.1. Ignition/Vehicle » Off & Remove » Test lamp 8.2. Disconnect the electrical connector: X2 @ K20 Engine Control Module 8.3. Test for infinite resistance between the test points: Control circuit terminal 1 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 8.4. Test for less than 2 Ω between the test points: Control circuit terminal 1 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇓ If less than 2 Ω 8.5. Ignition » On / Vehicle » In Service Mode 8.6. Test for less than 1 V between the test points: Control circuit terminal 1 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If the test lamp flashes
  13. Test or replace the component: Q61 Reductant Injector Component Testing Static Test
  14. Ignition/Vehicle » Off
  15. Disconnect the electrical connector: Q61 Reductant Injector
  16. Test for 10 to 18 Ω between the test points: Control terminal 1 & Control terminal 2 ⇒ If not between 10 and 18 Ω Replace the component: Q61 Reductant Injector ⇓ If between 10 and 18 Ω
  17. Test for less than 500 K Ω between the test points: Each terminal of the component & The component’s housing Replace the component: Q61 Reductant Injector ⇓ If greater than 500 K Ω
  18. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Reductant Fluid Injector Replacement — Q61 Reductant Injector For control module replacement, programming, and setup refer to: Control Module References Additional Procedures Reductant System Tamper Service Bay Test — Perform only when the following warning message is displayed: Service Emission System / Service Exhaust Fluid System