Case IH 19346 – Engine Control Module (ECM) or Vehicle Control Module (VCM): Timeout error of CAN receive frame HCUData (Heater Control Unit Data)

This fault code indicates a Controller Area Network (CAN) communication failure. The Engine Control Module (ECM) or Vehicle Control Module (VCM) is not receiving the expected data frames from the Heater Control Unit (HCU) within the required timeframe.

• Tier 4b
• Puma
• Magnum
• Optum
• Steiger
• Vestrum
• Farmall
• N-Series Tractor Loader Backhoes (TLBs)
• T4
• T7
• T8

1. 1

   Check HCU power and ground to verify the module is receiving proper battery voltage and has a solid ground

2. 2

   Inspect the CAN Hi and CAN Lo wiring harness between the HCU and the ECM for chafed wires, open circuits, or shorts to ground/power

3. 3

   Inspect HCU and ECM connectors for moisture intrusion, DEF corrosion, pushed-back pins, or bent terminals

4. 4

   Check CAN terminating resistors at the diagnostic port (should be approximately 60 ohms with the battery disconnected)

1. 1

   Power Down

   Turn off the ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the HCU

   Find the DEF Heater Control Unit, which is usually situated near the DEF tank assembly or integrated into the DEF supply module bracket.

3. 3

   Disconnect and Isolate

   Unplug the electrical connector from the HCU.

4. 4

   Perform Continuity Testing

   If your diagnostic checks revealed a broken CAN wire or missing power/ground, repair the damaged section of the wiring harness or replace the corroded connector pigtail.

5. 5

   Replace the HCU

   If the harness tests perfectly (good power, good ground, intact CAN lines), the internal CAN transceiver in the HCU has likely failed. Unbolt the faulty HCU and install the replacement unit.

6. 6

   Reassemble

   Plug the harness back into the new HCU, ensuring the weather seal is seated correctly and the locking tab clicks into place.

7. 7

   Clear Codes

   Reconnect the battery. Turn the key to the ON position. Use a compatible diagnostic scanner (such as the Case IH EST or Jaltest Agricultural tool) to clear the inactive 19346 fault code.

8. 8

   Verify Operation

   Start the engine and monitor the DEF system data on the diagnostic tool to ensure the ECM is successfully receiving data from the HCU.