Case IH 3537 – Engine Control Unit (ECU / EDC): CAN Message timeout DM1DCU (from DCU) - CAN timeout

The Engine Control Unit (ECU) has lost communication with the Dosing Control Unit (DCU) over the Controller Area Network (CAN) bus.

• Magnum series (e.g., 235–340 Series 4)
• Steiger series
• Puma and Maxxum series
• Axial-Flow Combines (e.g., 7230, 8230, 9230)

1. 1

   Verify the tractor's battery voltage is sufficient, as low system voltage is a common cause of CAN communication timeouts.

2. 2

   Check the fuse box for any blown fuses or faulty relays that supply power to the DCU.

3. 3

   Inspect the wiring harness between the Engine ECU and the DCU for chafing, breaks, or melted sections.

4. 4

   Disconnect the DCU connector and inspect for water ingress, corrosion, bent pins, or pushed-out terminals.

5. 5

   With the battery disconnected, measure the resistance across the CAN High and CAN Low pins at the DCU connector (should read approximately 60 ohms).

6. 6

   Verify that the DCU is receiving proper voltage and has a clean ground connection to the chassis.

1. 1

   Disconnect battery

   Disconnect the machine's battery to prevent electrical damage.

2. 2

   Repair wiring

   If wiring damage is found during the diagnostic checks, repair the affected CAN bus wires or power/ground wires using approved CNH wiring repair connectors.

3. 3

   Clean connectors

   Clean any corroded connectors with electrical contact cleaner and apply dielectric grease before reconnecting.

4. 4

   Replace fuses or relays

   Replace any blown fuses or faulty power relays supplying the DCU.

5. 5

   Diagnose DCU failure

   If the wiring, power, and ground are all verified to be good, the DCU itself has likely failed internally and must be replaced.

6. 6

   Replace DCU

   Remove the mounting hardware securing the DCU (typically mounted near the DEF tank or on the frame) and install the new unit.

7. 7

   Reconnect battery

   Reconnect the battery.

8. 8

   Program new DCU

   Installing a new DCU requires the CNH Electronic Service Tool (EST) laptop software to flash the module, perform a software installation, and clear the inactive fault codes.