Case IH 3873 – Engine Control Module (ECM / EDC): Timeout of CAN message TSC1-TE passive

The engine controller stops receiving the expected torque and speed command messages from the transmission controller over the CAN bus network. It indicates a communication breakdown rather than a mechanical failure of the engine itself.

• Case IH Magnum Series (e.g., Magnum 235 – 340)
• Case IH Steiger
• Case IH Puma
• Case IH Optum

1. 1

   Perform a system-wide code scan to check for other active CAN bus communication fault codes (e.g., 'ECM Bus Off') to rule out a global network failure.

2. 2

   Visually inspect the CAN bus wiring harness between the Engine ECU and the Transmission Control Unit/Cab for chafing, pinched wires, or melted insulation.

3. 3

   Disconnect harness connectors at the ECU and TCU to inspect pins for corrosion, moisture ingress, or pushed-back terminals.

4. 4

   Perform a CAN bus resistance test with the battery disconnected by measuring resistance across CAN High and CAN Low pins at the diagnostic port (should be approximately 60 ohms).

1. 1

   Power Down

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

2. 2

   Isolate the Fault

   Based on the resistance test, locate the damaged section of the CAN bus wiring harness, the faulty connector, or the failed terminating resistor.

3. 3

   Repair Wiring

   If the wiring is damaged, repair the wires using OEM-approved splicing methods (e.g., soldering and heat shrink). Crucial: Ensure the twisted-pair configuration of the CAN wires is maintained to prevent electromagnetic interference.

4. 4

   Repair Connectors

   If connector pins are corroded or damaged, use a pin extraction tool to remove the faulty pins and crimp on new OEM replacement pins.

5. 5

   Replace Resistors

   If a terminating resistor is found to be faulty (causing a 120-ohm reading on the bus), plug in a replacement resistor module.

6. 6

   Reassemble

   Apply dielectric grease to the connector seals (do not pack it directly onto the pins) to prevent future moisture ingress, and securely reconnect all modules.

7. 7

   Clear Codes

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) to the diagnostic port, clear the inactive fault codes, and cycle the key.

8. 8

   Verify

   Start the engine and verify that the TSC1-TE CAN message is now being received and fault code 3873 does not return.