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Tahoe / Yukon Service Manual

DTC P143C, P20C1-P20C4, P221E, or P221F

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5507255 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 P143C Reductant Heater 3 Control Circuit Shorted DTC P20C1 Reductant Heater 3 Control Circuit DTC P20C2 Reductant Heater 3 Performance DTC P20C3 Reductant Heater 3 Control Circuit Low DTC P20C4 Reductant Heater 3 Control Circuit High DTC P221E Reductant Heater 3 Current Too Low DTC P221F Reductant Heater 3 Current Too High Circuit/System Description For an overview of the component/system, refer to: Exhaust Aftertreatment System Description

Circuit Description
Control — Terminal 10 The output circuit is switched to 12 V to activate the component.
Control — Terminal 15 The output circuit is switched to ground to enable the component(s).

Conditions for Running the DTC P143C, P20C2, P221E DTC P10C6, P10DA, P10DB, P10DC, P10DD, P10F4, P20FF, U2412, U2626 = Not set DTCs related to the following system/component = Not Set – B214 Reductant Temperature Sensor – Reductant Heater – Reductant Heater 2 No other DTCs related to the concerned component are set. Ignition On or Engine Running Ignition and Start Switch Signal = Greater than 11 V Reductant Heater 3 = On Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 12 s P20C1, P20C3, P20C4, P221F DTC P10F4, P20FF = Not set Ignition On or Engine Running Ignition and Start Switch Signal = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met — For greater than 4 s Conditions for Setting the DTC P143C Control Circuit Shorted to Control Circuit — For greater than 12 s P20C1 Control Circuit = Open — For greater than 1 s P20C2, P221F Control Circuit = High Current — For greater than 10 s P20C3 Control Circuit = Short to Ground — For greater than 1 s P20C4 Control Circuit = Short to Voltage — For greater than 1 s P221E Control Circuit = Low Current — For greater than 4 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC — Additional actions taken: Driver Information Display = Service Emission System / Service Exhaust Fluid System Reductant Heater 3 = Disabled Reductant Injector = Disabled Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Diagnostic Aids If the control circuits of any reductant heater are shorted together, DTCs for all reductant heaters will be set and all the reductant heaters will be disabled. 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 Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify DTC P10C6, P10DA, P10DB, P10DC, P10DD, P10F4, P20FF, U2412, U2626 is not set. ⇒ If any of the DTCs are set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If none of the DTC are set
  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 & All vehicle systems » Off
  6. Disconnect the electrical connector: A38 Reductant Pump and Sensor Assembly
  7. Ignition » On / Vehicle » In Service Mode
  8. Test for 2.5 to 4.5 V between the test points: Control circuit terminal 10 & Ground ⇒ If less than 2.5 V 4.1. Ignition/Vehicle & All vehicle systems » Off 4.2. Disconnect the electrical connector: @ K115 Reductant Control Module 4.3. Test for infinite resistance between the test points: Control circuit terminal 10 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 4.4. Test for less than 2 Ω between the test points: Control circuit terminal 10 @ Component harness & Terminal 2 @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K115 Reductant Control Module ⇒ If greater than 4.5 V 4.1. Ignition/Vehicle & All vehicle systems » Off 4.2. Disconnect the electrical connector: @ K115 Reductant 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 10 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K115 Reductant Control Module ⇓ If between 2.5 and 4.5 V
  9. Connect a test lamp between the test points: Control circuit terminal 15 & B+
  10. Ignition » On / Vehicle » In Service Mode
  11. Verify the test lamp does not turn On. ⇒ If the test lamp turns On 7.1. Ignition/Vehicle » Off & Remove » Test lamp 7.2. Disconnect the electrical connector: @ K115 Reductant Control Module 7.3. Test for infinite resistance between the test points: Control circuit terminal 15 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇒ If infinite resistance » Replace the component: K115 Reductant Control Module ⇓ If the test lamp does not turn On
  12. Connect a test lamp between the test points: Control circuit terminal 15 & Ground
  13. Ignition » On / Vehicle » In Service Mode
  14. Verify the test lamp does not turn On. ⇒ If the test lamp turns On 10.1. Ignition/Vehicle » Off & Remove » Test lamp 10.2. Disconnect the electrical connector: @ K115 Reductant Control Module 10.3. Ignition » On / Vehicle » In Service Mode 10.4. Test for less than 1 V between the test points: Control circuit terminal 15 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K115 Reductant Control Module ⇓ If the test lamp does not turn On
  15. Disconnect the electrical connector: @ K115 Reductant Control Module
  16. Test for less than 2 Ω between the test points: Control circuit terminal 15 @ Component harness & Terminal 14 @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇓ If less than 2 Ω
  17. Test or replace the component: A38 Reductant Pump and Sensor Assembly
  18. 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 Replace the component: K115 Reductant Control Module ⇓ If the DTC is not set
  19. All OK. Component Testing Static Test
  20. Ignition/Vehicle » Off
  21. Disconnect the electrical connector: A38 Reductant Pump and Sensor Assembly
  22. Test for 1 to 6 Ω between the test points: Control terminal 10 & Control terminal 15 ⇒ If not between 1 and 6 Ω Replace the component: A38 Reductant Pump and Sensor Assembly ⇓ If between 1 and 6 Ω
  23. Test for infinite resistance between the test points: Each terminal of the component & The component’s housing ⇒ If less than infinite resistance Replace the component: A38 Reductant Pump and Sensor Assembly ⇓ If infinite resistance
  24. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Reductant Control Module Replacement — K115 Reductant Control Module Emission Reduction Fluid Tank Replacement — A38 Reductant Pump and Sensor Assembly For control module replacement, programming, and setup refer to: Control Module References Additional Procedures Perform the scan tool control function: Reductant System Tamper Service Bay Test — Perform only when the following warning message is displayed: Service Emission System / Service Exhaust Fluid System