Case IH 3874 – Engine ECU: Timeout of CAN message TSC1-AR passive

Communication error on the machine's Controller Area Network (CAN bus). The Engine Control Unit is expecting to receive a specific Torque Speed Control (TSC1-AR) message from another controller (such as the Transmission Control Unit or Armrest Controller). When this message is not received within the programmed timeframe, the ECU logs a timeout error.

• Magnum
• Puma
• Maxxum
• CVX
• Quadtrac

1. 1

   Check for accompanying codes indicating the TCU or Armrest Controller is disconnected from the CAN bus, which would point to a broader network failure.

2. 2

   Inspect the CAN bus wiring harness between the Engine ECU and the transmitting module (TCU/Vehicle ECU) for chafing, broken wires, or melted insulation.

3. 3

   Check the ECU and TCU connectors for moisture, corrosion, or pushed-back pins.

4. 4

   Perform a CAN Bus Resistance Test with the battery disconnected by measuring resistance across the CAN High and CAN Low pins at the diagnostic port (should read approx 60 ohms; 120 ohms indicates a missing terminating resistor or broken wire, 0 ohms indicates a short circuit).

5. 5

   Verify that the CAN bus is not shorted to ground or shorted to the battery voltage.

1. 1

   Disconnect Power

   Disconnect the machine's battery to prevent electrical damage during testing and repair.

2. 2

   Isolate the Fault

   Using a multimeter, test the continuity of the CAN High and CAN Low wires from the Engine ECU harness to the Transmission/Vehicle controller harness.

3. 3

   Repair Wiring

   If a break or short is found in the wiring, splice in a new section of twisted-pair CAN wire using heat-shrink butt connectors, or replace the damaged harness section entirely.

4. 4

   Clean Connections

   Spray the ECU and TCU connector pins with electrical contact cleaner. Ensure all pins are seated tightly and apply dielectric grease to the connector seals to prevent moisture intrusion.

5. 5

   Check/Replace Resistors

   If the CAN resistance test failed, locate and replace the faulty CAN bus terminating resistor.

6. 6

   Clear Codes

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

7. 7

   Test Run

   Start the engine and operate the machine to verify the code does not return. If the wiring is 100% intact and the code persists, the transmitting module or the Engine ECU itself may have an internal failure requiring reprogramming or replacement.