Case IH 19606 – DCU (Dosing Control Unit): CAN receive frame ET1 (Oil and Water temp engine) | too many CAN messages | P0600 Serial Communication Link

This is a CAN bus communication error. It indicates that the control module is being overloaded with an excessive number of CAN messages specifically related to the ET1 data frame (which broadcasts engine oil and water temperature data) over the P0600 serial communication link.

• Tier 4a
• Magnum 235–340 (Series 4)
• Steiger 350–600
• Puma series
• Farmall A Series
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230

1. 1

   Check for accompanying active CAN codes (e.g., 19605 timeout, 19607 signal out of range, or general P0600 serial link codes) which point to a physical CAN bus failure rather than a single module issue.

2. 2

   Inspect the wiring harness and connectors between the Engine ECU and the DCU for chafed wires, corrosion, or water ingress.

3. 3

   With batteries disconnected, test CAN Bus resistance across the CAN High and CAN Low pins (should read approximately 60 ohms; 120 ohms indicates a faulty terminating resistor or open circuit).

4. 4

   Verify if there are any pending software updates for the Engine ECU or DCU, as a software glitch can cause the Engine ECU to spam the network with ET1 frames.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery ground cable to prevent electrical spikes.

2. 2

   Clean Connections

   Disconnect the harnesses at the DCU (often located near the DEF tank or under the cab steps depending on the model) and the Engine ECU. Clean the pins with electronic contact cleaner and apply dielectric grease.

3. 3

   Repair Harness

   If continuity testing reveals a short or open circuit in the CAN lines between the ECU and DCU, repair or replace the damaged section of the wiring harness.

4. 4

   Update Software

   If the wiring is intact, connect the CNH Electronic Service Tool (EST). Reflash/update the software on both the Engine ECU and the DCU. CNH often releases patches for CAN communication logic errors.

5. 5

   Replace the DCU

   If the wiring is perfect, the software is up to date, and the DCU is still failing to process the ET1 frame correctly (or the Engine ECU is confirmed to be hardware-failing and spamming the bus), the faulty module must be replaced. Note: A new DCU requires dealer software installation and parameter programming to function.