Case IH 19876 – HCU (Heater Control Unit): PRC low for voltage at DEF/AdBlue Supply module Heater (via HCU)

The voltage detected on the circuit for the Diesel Exhaust Fluid (DEF) Supply Module Heater has dropped below the minimum acceptable range, indicating a failure in the electrical supply or the heater element itself.

• Tier 4b
• 580N
• 580SN
• 590SN
• 570N EP

1. 1

   Verify battery and Terminal 30 voltage to ensure the system is receiving proper overall voltage (low voltage can disable power stage diagnostics)

2. 2

   Inspect the wiring harness and connectors going to the DEF Supply Module Heater for corrosion, chafing, or loose pins

3. 3

   Disconnect the DEF Supply Module Heater and test the resistance (Ohms) of the heating element using a multimeter (an open circuit or dead short indicates a failed element)

4. 4

   Check the voltage output from the Heater Control Unit (HCU) to the DEF supply module to ensure the HCU is sending the correct voltage

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Module

   Locate the DEF Supply Module (Dosing Module) on the machine, which houses the supply pump and the integrated heater.

3. 3

   Disconnect

   Unplug the electrical connector specifically routed to the DEF Supply Module Heater.

4. 4

   Repair/Replace

   If the diagnostic tests revealed a wiring issue, repair the damaged section of the harness. If the heater element failed the resistance test, remove the DEF Supply Module/Heater assembly.

5. 5

   Install

   Mount the new DEF Supply Module or Heater assembly and secure the fluid lines and electrical connectors.

6. 6

   Relearn/Program

   Reconnect the battery. Note: If the entire DEF Dosing Supply Module is replaced, the new module may need to be programmed/calibrated to the vehicle's ECM using the Case Electronic Service Tool (EST).

7. 7

   Clear Codes

   Use a diagnostic tool to clear the 19876 fault code. Run the machine to ensure the code does not return.