Case IH DCU19578 – DCU: CAN Receive Signal: Dosing Status Not in Range

The Dosing Control Unit (DCU) has detected that the dosing status signal received over the CAN bus is outside of its expected or plausible range. This indicates a communication error between the Selective Catalytic Reduction (SCR) system components, meaning critical information about the DEF dosing system operation is either lost or contains invalid data.

• Magnum 235
• Magnum 290
• Magnum 340
• Puma Series
• Quadtrac Series

1. 1

   Review other active fault codes in the DCU or ECU (e.g., NOx sensors, DEF pressure, DEF pump performance) which may provide additional diagnostic clues

2. 2

   Check battery voltage (should be 12.4V+ with engine off, 13.5-14.5V running) and inspect main ground connections for the cab, engine, and chassis

3. 3

   Inspect DEF quality for poor quality or crystallization

4. 4

   Visually inspect the SCR system wiring harnesses for damage, chafing, heat damage, or corrosion, especially the loom running along the engine

5. 5

   Disconnect and inspect electrical connectors at the DCU and main ECU for corroded, bent, or loose pins

6. 6

   Perform a CAN bus resistance check with the battery disconnected (should be approximately 60 ohms between CAN High and CAN Low; a reading of 120 ohms indicates a missing terminating resistor or a break, while near 0 ohms indicates a short circuit)

7. 7

   Use the Case IH Electronic Service Tool (EST) to monitor the CAN network and perform a Urea Dosing System Test

1. 1

   Address other active faults

   Diagnose and repair any other SCR-related faults first, as they could be the root cause of the communication error.

2. 2

   Repair wiring and connectors

   Repair or replace any damaged wiring or corroded connectors found during the visual inspection. Ensure all connections are clean and secure.

3. 3

   Verify module power and ground

   Confirm that the DCU and ECU have a stable power supply and a solid ground connection.

4. 4

   Perform module reset

   Clear all fault codes using a diagnostic tool. Perform a hard reset by disconnecting the battery for 15-30 minutes to clear intermittent communication glitches.

5. 5

   Update software

   Check with a Case IH dealer for any available software or firmware updates for the DCU or ECU.

6. 6

   Replace DCU

   If all wiring and communication links are verified intact and the fault persists, replace the Dosing Control Unit (DCU) as a last resort.