DTC P20B9-P20BF or P20C0-P20C4

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Jayson McKinney
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1 Page 1 of Chevrolet Silverado 2500/3500-4WD Document ID: DTC P20B9-P20BF or P20C0-P20C4 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptors DTC P20B9 Reductant Heater 1 Control Circuit DTC Reductant Heater 1 Performance DTC P20BB Reductant Heater 1 Control Circuit Low Voltage DTC P20BC Reductant Heater 1 Control Circuit High Voltage DTC P20BD Reductant Heater 2 Control Circuit DTC P20BF Reductant Heater 2 Control Circuit Low Voltage DTC P20C0 Reductant Heater 2 Control Circuit High Voltage DTC P20C1 Reductant Heater 3 Control Circuit DTC P20C3 Reductant Heater 3 Control Circuit Low Voltage DTC P20C4 Reductant Heater 3 Control Circuit High Voltage Diagnostic Fault Information Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance DEF Pump Heater Control * P20C General Motors. All rights reserved. P20C1, P20C4

2 Page 2 of 8 Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance DEF Line Heater Control * P20BD P20BD, P20C0 DEF Tank Heater Control * P20B9 P20B9, P20BC Ground * Glow Plug Control Module (GPCM) fuse opens Circuit/System Description As reductant will freeze at temperatures below 0 C (32 F), there are 3 reductant heaters. Reductant heater 1 is in the reductant reservoir, reductant heater 2 is in the supply line to the reductant injector, and reductant heater 3 is at the reductant pump. The ECM monitors the reductant temperature sensor located within the reservoir in order to determine if reductant temperature is below its freeze point. If the ECM determines that the reductant may be frozen, it signals the Glow Plug Control Module (GPCM) to energize the reductant heaters. The selective catalyst 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 reductant 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 in parts per million (ppm). The ECM then adjusts the amount of reductant injected upstream of the SCR based on the NOx concentration. Engine-out NOx levels as measured by NOx Sensor 1 will either increase (high ppm) or decrease (low ppm) the amount of reductant injected. The NOx concentration as measured by NOx Sensor 2 provides the ECM with both an indication of the NOx conversion efficiency within the SCR as well as confirming proper operation of the reductant system. Conditions for Running the DTCs P20B9, P20BD, or P20C1 DTC P220B is not set. Reductant heater is commanded On. Glow plug control module temperature is less than 123 C (254 F). Glow plug control module battery voltage is between 7 16 V. The DTCs run continuously once the above conditions are met. DTC P205B, P205C, and P205D are not set. Emission reduction fluid tank heaters are active for 1,000 3,000 s. Emission reduction fluid tank level sensor reading is 100 %. Emission reduction fluid tank temperature is colder than 16 C (3 F). Vehicle speed is greater than 5 km/h (3 mph). Battery voltage is greater than 11 V. Engine speed is greater than 600 RPM. P20BB, P20BF, or P20C3

3 Page 3 of 8 DTC P220B is not set. Reductant heater is commanded On. Glow plug control module temperature is less than 123 C (254 F). Glow plug control module battery voltage is between V. The DTCs run continuously once the above conditions are met. P20BC, P20C0, or P20C4 The reductant heater is commanded Off. Conditions for Setting the DTC P20B9, P20BD, or P20C1 The ECM receives a GPCM serial data message indicating the heater control circuit is open for greater than 3 s. The ECM receives a GPCM serial data message indicating the heater temperature difference between the start temperature and current temperature is less than a predetermined value. P20BB, P20BF, or P20C3 The ECM receives a GPCM serial data message indicating the heater control circuit is shorted to ground or overloaded for greater than 1 s. P20BC, P20C0, or P20C4 The ECM receives a GPCM serial data message indicating the heater control circuit is shorted to a voltage for greater than 2 s. Action Taken When the DTC Sets DTCs P20B9, P20BB, P20BC, P20BD, P20BF, P20C0, P20C1, P20C3, and P20C4 are Type A DTCs. DTC is a Type B DTC. The ECM commands the engine to operate in Reduced Engine Power mode. The driver information center may display the Engine Power Is Reduced message. Conditions for Clearing the DTC DTCs P20B9, P20BB, P20BC, P20BD, P20BF, P20C0, P20C1, P20C3, and P20C4 are Type A DTCs. DTC is a Type B DTC. Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Component Connector End Views Component View Reference Powertrain Component Views

4 Page 4 of 8 Description and Operation Diesel Exhaust Fluid (DEF) Warning Strategy Exhaust Aftertreatment System Description 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 for scan tool information. Circuit/System Verification Note: Reductant Heater parameters are in the GPCM data list. 1. Ignition On. Note: Clear the DTCs with a scan tool prior to commanding any reductant system output control. The reductant system output control functions will not operate if a DTC is set. 2. Verify the parameters listed below do not display Malfunction when commanding the appropriate Reductant Heater 1, 2, or 3 On and Off with a scan tool. Reductant Heater 1, 2, or 3 Control Circuit Low Voltage Test Status Reductant Heater 1, 2, or 3 Control Circuit Open Test Status Reductant Heater 1, 2, or 3 Control Circuit Short Volts Test Status If Malfunction is displayed Refer to Circuit/System Testing. If Malfunction is not displayed 3. Verify the appropriate scan tool Reductant Heater 1, 2, or 3 Current parameter is within the range specified below when commanding the Reductant Heater 1, 2, or 3 On with a scan tool. Reductant Heater A Reductant Heater A Reductant Heater A If not within the specified range Refer to Circuit/System Testing If within the specified range 4. 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. 5. Verify a DTC does not set. If a DTC sets Refer to Circuit/System Testing If a DTC does not set 6. All OK.

5 Page 5 of 8 Circuit/System Testing Note: When testing the low reference circuits, verify all vehicle systems are completely Off for at least 2 minutes. This includes retained accessory power (RAP) and the scan tool. Refer to Testing Ground and Low Reference Circuits for further information on testing the low reference circuits. 1. Ignition Off and all vehicle systems Off, disconnect the X way harness connector at the Reductant Tank. It may take up to 2 min for all vehicle systems to power down. Refer to Inline Harness Connector End Views for connector identification. Note: Testing for steps 2 7 is performed on the Glow Plug Control Module side of the harness connector. 2. Test for less than 5 Ω between the appropriate ground circuit terminal listed below and ground: Reductant heater 1 (reservoir) ground circuit terminal C4 Reductant heater 2 (line) ground circuit terminal B4 Reductant heater 3 (pump) ground circuit terminal A4 If 5 Ω or greater 2.1. Test for less than 2 Ω in the ground circuit end to end. If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, repair the open/high resistance in the ground connection. If less than 5 Ω 3. Verify that a test lamp does not illuminate between the appropriate circuit terminals listed below: Reductant heater 1 (reservoir) ground circuit terminal C4 and control circuit terminal C5 Reductant heater 2 (line) ground circuit terminal B4 and control circuit terminal B5 Reductant heater 3 (pump) ground circuit terminal A4 and control circuit terminal A5 If the test lamp illuminates 3.1. Ignition Off, remove the test lamp, disconnect the harness connector at the K34 Glow Plug Control Module, ignition On Test for less than 1 V between the control circuit and ground. If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K34 Glow Plug Control Module If the test lamp does not illuminate 4. Remove the test lamp. Note: Clear the DTCs with a scan tool prior to commanding any reductant system output control. The reductant system output control functions will not operate if a DTC is set. 5. Verify the appropriate scan tool Reductant Heater 1, 2, or 3 Control Circuit Low Voltage Test Status parameter is OK when commanding the Reductant Heater 1, 2, or 3 On with a scan tool. If OK is not displayed 5.1. Ignition Off, disconnect the harness connector at the K34 Glow Plug Control Module Test for infinite resistance between the control circuit and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K34 Glow Plug Control Module. If OK is displayed 6. Install a 3 A fused jumper wire between the appropriate circuit terminals listed below.

6 Page 6 of 8 Reductant heater 1 (reservoir) ground circuit terminal C4 and control circuit terminal C5 Reductant heater 2 (line) ground circuit terminal B4 and control circuit terminal B5 Reductant heater 3 (pump) ground circuit terminal A4 and control circuit terminal A5 7. Verify the scan tool Reductant Heater 1, 2, or 3 Control Circuit Low Voltage Test Status parameter is Malfunction when commanding the Reductant Heater 1, 2, or 3 On with a scan tool. If Malfunction is not displayed 7.1. Ignition Off, remove the jumper wire, disconnect the harness connector at the K34 Glow Plug Control Module Test for less than 2 Ω in the control circuit end to end. If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K34 Glow Plug Control Module If Malfunction is displayed Note: Testing on the X way harness connector for the remaining steps is performed on the reductant reservoir side of the harness. It may be necessary to remove the diesel exhaust fluid reservoir to perform the testing. 8. Disconnect the harness connector at the appropriate reductant heater. 9. Test for less than 2 Ω between the appropriate terminal listed below: Reductant heater 1 (reservoir) ground circuit terminal A or 1 and X way harness connector terminal C4 Reductant heater 2 (line) ground circuit terminal A and X way harness connector terminal B4 Reductant heater 3 (pump) ground circuit terminal 1 and X way harness connector terminal A4 If 2 Ω or greater Repair the open/high resistance in the circuit. If less than 2 Ω 10. Test for less than 2 Ω between the appropriate terminals listed below: Reductant heater 1 (reservoir) control circuit terminal B or 2 and X way harness connector terminal C5 Reductant heater 2 (line) ground circuit terminal B and X way harness connector terminal B5 Reductant heater 3 (pump) ground circuit terminal 2 and X way harness connector terminal A5 If 2 Ω or greater Repair the open/high resistance in the circuit. If less than 2 Ω 11. Test for infinite resistance between the appropriate terminals listed below and ground: Reductant heater 1 (reservoir) control circuit terminal B. Reductant heater 2 (line) ground circuit terminal B. Reductant heater 3 (pump) ground circuit terminal 2. If less than infinite resistance Repair the short to ground in the circuit. If Infinite resistance 12. Connect the X way harness connector at the Reductant Tank, ignition On.

7 Page 7 of Test for less than 1 V between the appropriate reductant heater control circuit terminal listed below and ground: Reductant heater 1 (reservoir) control circuit terminal B. Reductant heater 2 (line) ground circuit terminal B. Reductant heater 3 (pump) ground circuit terminal 2. If 1 V or greater Repair the short to voltage on the circuit. If less than 1 V 14. Test or replace the reductant heater. Component Testing 1. Ignition Off, disconnect the harness connector at the appropriate reductant heater. 2. Test for the resistance between the control circuit terminal and the ground terminal as listed below: Reductant heater 1 (reservoir) 2 4 Ω Reductant heater 2 (line) 8 10 Ω. Reductant heater 3 (pump) 3 5 Ω If not within the specified range Replace the reductant heater. If within the specified range 3. All OK Repair Instructions Emission Reduction Fluid Exhaust Front Pipe Injector Supply Pipe Replacement for E52 Reductant Line Heater Emission Reduction Fluid Tank Reservoir Replacement for E53 Reductant Tank Heater Emission Reduction Fluid Supply Pump Module Replacement for the reductant pump heater Perform the scan tool Reductant System Reset procedure after replacing the A38 Emission Reduction Fluid Supply Pump Module. Control Module References for glow plug 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. Note: The diesel exhaust fluid (DEF) and ambient air temperatures must be greater than 7 C (19 F) before proceeding with this procedure. Exhaust Gas Temperature (EGT) sensor 2 must be less than 200 C (392 F) prior to running the Reductant System Leak Test. 5. Ignition On, command the Reductant System Leak Test On with a scan tool. Allow the pressure to build for at least 2 minutes. Observe the scan tool Reductant Pressure sensor parameter. The reading should be between kpa (58-94 psi) and there should be no leaks in the system.

8 Page 8 of 8 If not within the specified range or a leak is found A condition with the system still exists If within the specified range and no leak is found 6. Perform the Reductant System Malfunction Service Bay Test with a scan tool in order to clear the Service Emission System message, if illuminated. If the Service Emission System message does not turn Off A condition with the system still exists If the Service Emission System message turns Off 7. All OK.

DTC P20EE, P249D, P249E, or P2BAD

Page 1 of 7 Document ID: 2614257 DTC P20EE, P249D, P249E, or P2BAD Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based