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Test Procedure

WARNING: This page is about a different car, the 2020 Ford F-550 Super Duty, 2020 Ford F-450 Super Duty, 2020 Ford F-350 Super Duty, 2020 Ford F-250 Super Duty, and 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
  1. RH1 PRELIMINARY DIAGNOSIS 

    Are DTCs P209F, P20B9, P20BA, P20BB, P20BC, P20BD, P20BE, P20BF, P20C0, P20C1, P20C2, P20C3, P20C4, P214F, P21C2, P21C3, P21C4, P21C7, P21DD, P221C or P221D present? 

    Yes No
    For F-150 and F-Series Super Duty, GO to  RH25.
    For F-650/F-750 with DTCs P20BD, P20BF, P20BE, P20C0, P221C or P221D, GO to  RH16.
    For F-650/F-750 with DTCs P209F, P20B9, P20BA, P20BB, P20BC, P214F or P21DD, GO to  RH12.
    For Transit and Transit Connect, GO to  RH8.
    For all others, GO to  RH2.    		 RETURN to SYMPTOM CHARTS for further direction.
  2. RH2 CHECK THE REDUCTANT HEATER RELAY 
    • Carry out the reductant heater relay component test. Refer to the Component Testing article.

    Is a concern present? 

    Yes No
    INSTALL a new Reductant Heater relay.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.    		 GO to  RH3.
  3. RH3 CHECK THE REDUCTANT HEATER RELAY B+ CIRCUIT 
    • Reductant Heater Relay connector disconnected.
    • Measure the voltage between:
      (+) Reductant Heater Relay Connector, Harness Side (-)
      B+ - Pin 3 Ground

    Is the voltage greater than 10.5 V? 

    Yes No
    GO to  RH4. REPAIR the open circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.
  4. RH4 CHECK THE REDUCTANT HEATER RELAY GND CIRCUIT 
    • Measure the resistance between:
      (+) Reductant Heater Relay Connector, Harness Side (-)
      GND - Pin 2 Ground

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  RH5. REPAIR the open circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.
  5. RH5 CHECK THE REDUCTANT HEATER RELAY CIRCUITS FOR AN OPEN 
    • GPCM-C connector disconnected.
    • Measure the resistance between:
      (+) Reductant Heater Relay Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRPWR - Pin 5 RDHTRPWR - Pin 16
      RDHTRCTRL - Pin 1 RDHTRCTRL - Pin 2

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  RH6. REPAIR the open circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.
  6. RH6 CHECK THE REDUCTANT HEATER RELAY CIRCUITS FOR A SHORT TO GROUND 
    • Measure the resistance between:
      (+) GPCM-C Connector, Harness Side (-)
      RDHTRPWR - Pin 16 Ground
      RDHTRCTRL - Pin 2 Ground

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to  RH7. REPAIR the short circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.
  7. RH7 CHECK THE REDUCTANT HEATER RELAY CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) GPCM-C Connector, Harness Side (-)
      RDHTRPWR - Pin 16 Ground
      RDHTRCTRL - Pin 2 Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.    		 GO to  RH37.
  8. RH8 CHECK THE REDUCTANT DOSAGE CONTROL MODULE FOR VOLTAGE 
    • Ignition OFF.
    • Reductant Dosage Control Module connector disconnected.
    • Connect a 5 amp fused jumper wire between the following:
      Point A Reductant Dosage Control Module Connector, Harness Side Point B
      RDCMRC Ground
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Reductant Dosage Control Module Connector, Harness Side (-)
      VPWR Ground

    Is the voltage greater than 10.5 V? 

    Yes No
    For Transit and Transit Connect with DTCs P20BD, P20BE, P20BF, P20C0, P221C or P221D. GO to  RH16.
    For Transit with DTC P20C1, P20C2, P20C3 or P20C4, GO to  RH20.
    For all others, GO to  RH12.    		 GO to  RH9.
  9. RH9 CHECK THE VOLTAGE TO THE REDUCTANT DOSAGE CONTROL MODULE RELAY 
    • Ignition OFF.
    • Reductant Dosage Control Module Relay connector disconnected.
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Reductant Dosage Control Module Relay Connector, Harness Side (-)
      B+ - Pin 1, 3 Ground

    Is the voltage greater than 10.5 V? 

    Yes No
    GO to  RH10. REPAIR the open circuit.
    Clear the RDCM and PCM DTCs. REPEAT the self-test.
  10. RH10 CHECK THE REDUCTANT DOSAGE CONTROL MODULE RELAY 
    • Carry out the reductant dosage control module relay component test. Refer to the Component Testing article.

    Is a concern present? 

    Yes No
    INSTALL a new Reductant Dosage Control Module relay.
    Clear the RDCM and PCM DTCs. REPEAT the self-test.    		 GO to  RH11.
  11. RH11 CHECK THE REDUCTANT DOSAGE CONTROL MODULE CIRCUITS FOR AN 

    OPEN 

    • Ignition OFF.
    • Measure the resistance between:
      (+) Reductant Dosage Control Module Relay Connector, Harness Side (-) Reductant Dosage Control Module Connector, Harness Side
      VPWR - Pin 5 VPWR
    • Measure the resistance between:
      (+) Reductant Dosage Control Module Connector, Harness Side (-)
      PWRGND Ground

    Is the resistance less than 5 ohms? 

    Yes No
    The system is operating correctly at this time.
    The concern may have been caused by a loose or corroded connector.    		 REPAIR the open circuit.
    Clear the RDCM and PCM DTCs. REPEAT the self-test.
  12. RH12 CHECK THE REDUCTANT TANK HEATER CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • For Transit Connect,
    • Reductant Dosage Control Module connector disconnected.
    • Reductant Quality Module connector disconnected.
    • Measure the resistance between:
      (+) Reductant Quality Module Connector, Harness Side (-) Reductant Dosage Control Module Connector, Harness Side
      RDHTRC1 RDHTRC1
    • Measure the resistance between:
      (+) Reductant Quality Module Connector, Harness Side (-)
      GND Ground
    • For Transit,
    • Reductant Dosage Control Module connector disconnected.
    • Reductant Heater and Sender Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Heater and Sender Assembly Connector, Harness Side (-) Reductant Dosage Control Module Connector, Harness Side
      RDHTRC1 - Pin 1 RDHTRC1
    • Measure the resistance between:
      (+) Reductant Heater and Sender Assembly Connector, Harness Side (-)
      GND - Pin 2 Ground
    • For all others,
    • GPCM-C connector disconnected.
    • Reductant Pump Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRC1 RDHTRC1 - Pin 15
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      GND Ground

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  RH13. REPAIR the open circuit.
    For Transit and Transit Connect, clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, clear the GPCM and PCM DTCs.
    REPEAT the self-test.
  13. RH13 CHECK THE RDHTRC1 CIRCUIT FOR A SHORT TO GROUND 
    • For Transit Connect,
    • Measure the resistance between:
      (+) Reductant Quality Module Connector, Harness Side (-)
      RDHTRC1 Ground
    • For Transit,
    • Measure the resistance between:
      (+) Reductant Heater and Sender Assembly Connector, Harness Side (-)
      RDHTRC1 - Pin 1 Ground
    • For all others,
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      RDHTRC1 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  RH14. REPAIR the short circuit.
    For Transit and Transit Connect, clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, clear the GPCM and PCM DTCs.
    REPEAT the self-test.
  14. RH14 CHECK THE REDUCTANT TANK HEATER CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • For Transit Connect,
    • Measure the voltage between:
      (+) Reductant Quality Module Connector, Harness Side (-)
      RDHTRC1 Ground
      GND Ground
    • For Transit,
    • Measure the voltage between:
      (+) Reductant Heater and Sender Assembly Connector, Harness Side (-)
      RDHTRC1 - Pin 1 Ground
      GND - Pin 2 Ground
    • For all others,
    • Measure the voltage between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      RDHTRC1 Ground
      GND Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit.
    For Transit and Transit Connect, clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, clear the GPCM and PCM DTCs.
    REPEAT the self-test.    		 GO to  RH15.
  15. RH15 CHECK THE REDUCTANT TANK HEATER RESISTANCE 
    • Ignition OFF.
    • For Transit Connect,
    • Measure the resistance between:
      (+) Reductant Quality Module Connector, Component Side (-) Reductant Quality Module Connector, Component Side
      RDHTRC1 GND
    • For Transit,
    • Measure the resistance between:
      (+) Reductant Heater and Sender Assembly Connector, Component Side (-) Reductant Heater and Sender Assembly Connector, Component Side
      RDHTRC1 - Pin 1 GND - Pin 2
    • For all others,
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Component Side (-) Reductant Pump Assembly Connector, Component Side
      RDHTRC1 GND

    Is the resistance between 1 - 2.5 ohms (Transit and Transit Connect) or 1.33 - 1.66 ohms (all others)? 

    Yes No
    For Transit and Transit Connect, GO to  RH24.
    For all others, GO to  RH37.    		 For Transit, INSTALL a new Reductant Heater and Sender assembly. REFER to the Engine Emission Control article. Clear the RDCM and PCM DTCs.
    REPEAT the self-test.
    For Transit Connect, INSTALL a new Reductant Quality module. REFER to Engine Emission Control article. Clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, INSTALL a new Reductant Pump assembly. REFER to the Engine Emission Control article. Clear the GPCM and PCM DTCs. REPEAT the self-test.
  16. RH16 CHECK THE REDUCTANT PRESSURE LINE HEATER ASSEMBLY CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • For Transit and Transit Connect,
    • Reductant Dosage Control Module connector disconnected.
    • Reductant Pressure Line Heater Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-) Reductant Dosage Control Module Connector, Harness Side
      RDHTRC2 RDHTRC2
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      GND Ground
    • For all others,
    • GPCM-C connector disconnected.
    • Reductant Pressure Line Heater Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRC2 RDHTRC2 - Pin 13
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      GND Ground

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  RH17. REPAIR the open circuit.
    For Transit and Transit Connect, clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, clear the GPCM and PCM DTCs.
    REPEAT the self-test.
  17. RH17 CHECK THE RDHTRC2 CIRCUIT FOR A SHORT TO GROUND 
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      RDHTRC2 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  RH18. REPAIR the short circuit.
    For Transit and Transit Connect, clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, clear the GPCM and PCM DTCs.
    REPEAT the self-test.
  18. RH18 CHECK THE REDUCTANT PRESSURE LINE HEATER ASSEMBLY CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      RDHTRC2 Ground
      GND Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit.
    For Transit and Transit Connect, clear the RDCM and PCM DTCs. REPEAT the self-test.
    For all others, clear the GPCM and PCM DTCs.
    REPEAT the self-test.    		 GO to  RH19.
  19. RH19 CHECK THE REDUCTANT PRESSURE LINE HEATER RESISTANCE 
    • Ignition OFF.
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Component Side (-) Reductant Pressure Line Heater Assembly Connector, Component Side
      RDHTRC2 GND

    Is the resistance between 3 - 5 ohms? 

    Yes No
    For Transit and Transit Connect, GO to  RH24.
    For all others, GO to  RH37.    		 INSTALL a new Reductant Pressure Line Heater assembly. REFER to the Engine Emission Control article. Clear the GPCM and PCM DTCs.
    REPEAT the self-test.
  20. RH20 CHECK THE REDUCTANT PUMP ASSEMBLY CIRCUITS FOR AN OPEN 
    • Reductant Dosage Control Module connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-) Reductant Dosage Control Module Connector, Harness Side
      RDHTRC3 RDHTRC3
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      GND Ground

    Is the resistance less than 5 ohms? 

    Yes No
    GO to  RH21. REPAIR the open circuit.
    Clear the RDCM and PCM DTC. REPEAT the self-test.
  21. RH21 CHECK THE RDHTRC3 CIRCUIT FOR A SHORT TO GROUND 
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      RDHTRC3 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  RH22. REPAIR the short circuit.
    Clear the RDCM and PCM DTC. REPEAT the self-test.
  22. RH22 CHECK THE REDUCTANT PUMP ASSEMBLY CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Reductant Pump Assembly Connector, Harness Side (-) Reductant Pump Assembly Connector, Harness Side
      RDHTRC3 GND
    • Measure the voltage between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      GND Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit.  
    Clear the RDCM and PCM DTC. REPEAT the self-test. GO to  RH23.
  23. RH23 CHECK THE REDUCTANT PUMP ASSEMBLY HEATER RESISTANCE 
    • Ignition OFF.
    • Reductant Pump Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Component Side (-) Reductant Pump Assembly Connector, Component Side
      RDHTRC3 GND

    Is the resistance between 2.5 and 6 ohms? 

    Yes No
    GO to  RH24. INSTALL a new Reductant Pump assembly.
    REFER to the Engine Emission Control article.
    Clear the RDCM and PCM DTC. REPEAT the self-test.
  24. RH24 CHECK FOR CORRECT REDUCTANT DOSAGE CONTROL MODULE OPERATION 
    • Reductant Dosage Control Module connector disconnected.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect the reductant dosage control module connector and make sure it seats correctly.
    • Carry out the DCU self-test.
    • Verify the concern is still present.

    Is the concern still present? 

    Yes No
    INSTALL a new Reductant Dosage Control module. REFER to the Electronic Engine Controls article. The system is operating correctly at this time.
    The concern may have been caused by a loose or corroded connector.
  25. RH25 F-150 AND F-SERIES SUPER DUTY DIAGNOSIS 

    Are DTCs P209F, P20B9, P20BA, P20BB, P20BC, P20BD, P20BE, P20BF, P20C0, P20C1, P20C2, P20C3, P20C4, P214F, P21C2, P21C3, P21C4, P21C7, P21DD, P221C or P221D present? 

    Yes No
    For DTCs P20BD, P20BF, P20BE, P20C0, P221C or P221D, GO to  RH33.
    For DTCs P209F, P20B9, P20BA, P20BB, P20BC, P214F or P21DD, GO to  RH29.
    For all others, GO to  RH26.    		 RETURN to SYMPTOM CHARTS for further direction.
  26. RH26 CHECK THE BJB CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • For F-150,
    • BJB-B connector disconnected.
    • BJB-C connector disconnected.
    • BJB-D connector disconnected.
    • GPCM-C connector disconnected.
    • Measure the resistance between:
      (+) BJB-B Connector, Harness Side (-)
      GND Ground
    • Measure the resistance between:
      (+) BJB-C Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRCTRL - Pin 28 RDHTRCTRL - Pin 2
    • Measure the resistance between:
      (+) BJB-D Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRPWR - Pin 50 RDHTRPWR - Pin 16
    • For all others,
    • BJB-B connector disconnected.
    • GPCM-B connector disconnected.
    • Measure the resistance between:
      (+) BJB-B Connector, Harness Side (-)
      GND Ground
    • Measure the resistance between:
      (+) BJB-B Connector, Harness Side (-) GPCM-B Connector, Harness Side
      RDHTRCTRL RDHTRCTRL - Pin 28
      RDHTRPWR RDHTRPWR - Pin 14

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  RH27. REPAIR the open circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.
  27. RH27 CHECK THE REDUCTANT HEATER RELAY CIRCUITS FOR A SHORT TO GND 
    • For F-150,
    • Measure the resistance between:
      (+) GPCM-C Connector, Harness Side (-)
      RDHTRPWR - Pin 16 Ground
      RDHTRCTRL - Pin 2 Ground
    • For all others,
    • Measure the resistance between:
      (+) GPCM-B Connector, Harness Side (-)
      RDHTRPWR - Pin 14 Ground
      RDHTRCTRL - Pin 28 Ground

    Are the resistances greater than 10K ohms? 

    Yes No
    GO to  RH28. REPAIR the short circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.
  28. RH28 CHECK THE REDUCTANT HEATER CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • For F-150,
    • Measure the voltage between:
      (+) GPCM-C Connector, Harness Side (-)
      RDHTRPWR - Pin 16 Ground
      RDHTRCTRL - Pin 2 Ground
    • For all others,
    • Measure the voltage between:
      (+) GPCM-B Connector, Harness Side (-)
      RDHTRPWR - Pin 14 Ground
      RDHTRCTRL - Pin 28 Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit.
    Clear the GPCM and PCM DTCs. REPEAT the self-test.    		 GO to  RH37.
  29. RH29 CHECK THE RDHTRC1 CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • For F-150,
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRC1 RDHTRC1 - Pin 15
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      GND Ground
    • For all others,
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-) GPCM-B Connector, Harness Side
      RDHTRC1 RDHTRC1 - Pin 1
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      GND Ground

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  RH30. REPAIR the open circuit. Clear the GPCM and PCM DTCs. REPEAT the self-test.
  30. RH30 CHECK THE REDUCTANT TANK HEATER CIRCUITS FOR A SHORT TO GROUND 
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      RDHTRC1 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  RH31. REPAIR the short circuit. Clear the GPCM and PCM DTCs. REPEAT the self-test.
  31. RH31 CHECK THE RDHTRC1 CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Reductant Pump Assembly Connector, Harness Side (-)
      RDHTRC1 Ground
      GND Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit. Clear the GPCM and PCM DTCs. REPEAT the self-test. GO to  RH32.
  32. RH32 CHECK THE RDHTRC1 RESISTANCE 
    • Ignition OFF.
    • Reductant Pump Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pump Assembly Connector, Component Side (-) Reductant Pump Assembly Connector, Component Side
      RDHTRC1 GND

    Is the resistance between 1.33 - 1.66 ohms? 

    Yes No
    GO to  RH37. INSTALL a new Reductant Pump assembly.
    REFER to the Engine Emission Control article. Clear the GPCM and PCM DTCs. REPEAT the self-test.
  33. RH33 CHECK THE RDHTRC2 AND REDUCTANT PUMP ASSEMBLY CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • For F-150,
    • GPCM-C connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-) GPCM-C Connector, Harness Side
      RDHTRC2 RDHTRC2 - Pin 13
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      GND Ground
    • For all others,
    • GPCM-B connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-) GPCM-B Connector, Harness Side
      RDHTRC2 RDHTRC2 - Pin 22
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      GND Ground

    Are the resistances less than 5 ohms? 

    Yes No
    GO to  RH34. REPAIR the open circuit. Clear the GPCM and PCM DTCs. REPEAT the self-test.
  34. RH34 CHECK THE REDUCTANT PRESSURE LINE HEATER ASSEMBLY CIRCUIT FOR A SHORT TO GROUND 
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      RDHTRC2 Ground

    Is the resistance greater than 10K ohms? 

    Yes No
    GO to  RH35. REPAIR the short circuit. Clear the GPCM and PCM DTCs. REPEAT the self-test.
  35. RH35 CHECK THE RDHTRC2 AND REDUCTANT PUMP ASSEMBLY CIRCUITS FOR A SHORT TO VOLTAGE 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Reductant Pressure Line Heater Assembly Connector, Harness Side (-)
      RDHTRC2 Ground
      GND Ground

    Is any voltage present? 

    Yes No
    REPAIR the short circuit. Clear the GPCM and PCM DTCs. REPEAT the self-test. GO to  RH36.
  36. RH36 CHECK THE RDHTRC2 RESISTANCE 
    • Ignition OFF.
    • Reductant Pressure Line Heater Assembly connector disconnected.
    • Measure the resistance between:
      (+) Reductant Pressure Line Heater Assembly Connector, Component Side (-) Reductant Pressure Line Heater Assembly Connector, Component Side
      RDHTRC2 GND

    Is the resistance between 3 - 5 ohms? 

    Yes No
    GO to  RH37. INSTALL a new Reductant Pressure Line Heater assembly. REFER to the Engine Emission Control article. Clear the GPCM and PCM DTCs.
    REPEAT the self-test.
  37. RH37 CHECK FOR CORRECT GPCM OPERATION 
    NOTE: Not all vehicles have all components listed.
    • For F-Series Super Duty,
    • Disconnect all the GPCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the GPCM connectors and make sure they seat correctly.
    • BJB-B connector connected.
    • BJB-C connector connected.
    • Ignition ON, engine OFF.
    • Clear the PCM DTCs.
    • Carry out the PCM KOEO self-test.
    • Verify the concern is still present.
    • For all others,
    • Disconnect all the GPCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the GPCM connectors and make sure they seat correctly.
    • BJB-B connector connected.
    • BJB-C connector connected.
    • BJB-D connector connected.
    • Ignition ON, engine OFF.
    • Clear the PCM DTCs.
    • Carry out the KOER Glow Plug Monitor Self-Test using the scan tool.
    • Carry out the PCM KOEO self-test.
    • Verify the concern is still present.

    Is the concern still present? 

    Yes No
    INSTALL a new GPCM. Refer to the Glow Plug System article.
    Clear the PCM DTCs. REPEAT the self-test.    		 The system is operating correctly at this time.
    The concern may have been caused by a loose or corroded connector.
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