Case IH 19391 – Engine Control Module (ECM) / Engine Control Unit (ECU): CAN-Receive-Frame Torque / Speed control from ACC to ECM through TSC1_ACCR Message

This is a Controller Area Network (CAN) bus communication timeout error. The Engine Control Module (ECM) expects to receive continuous Torque/Speed Control (TSC1) command messages from the ACC (Armrest Control Computer / Auxiliary Control Computer). When the ECM stops receiving these specific data frames (TSC1_ACCR) within the expected time cycle, it logs this fault, meaning the engine computer has lost the throttle/torque command signal.

• Tier 4b
• Tier 4B (SCR/DEF) engines
• Case IH Magnum Series
• Case IH Puma Series
• Case IH Optum Series
• Case IH / CNH Wheel Loaders and Backhoes (e.g., STM N Series)

1. 1

   Verify battery voltage is within spec, as low voltage can disable module power stages and cause false CAN timeouts.

2. 2

   Look for other active CAN bus errors or ACC-specific fault codes to rule out a central CAN bus short or failed terminating resistor.

3. 3

   Perform a CAN Bus Resistance Test at the diagnostic port with the battery disconnected (should read approximately 60 ohms).

4. 4

   Perform a CAN Voltage Test with the battery reconnected and key ON (CAN-H and CAN-L should rest at approximately 2.5V).

5. 5

   Visually inspect the wiring harness between the Armrest/Vehicle controller and the Engine ECM for chafing, pinch points, or rodent damage.

1. 1

   Power Down

   Turn off the ignition and disconnect the negative battery cable.

2. 2

   Inspect Connectors

   Locate the ECM and the ACC modules. Disconnect the harness connectors at both modules.

3. 3

   Clean and Check Pins

   Inspect the connector pins for moisture intrusion, corrosion, or pushed-back pins (a very common cause of intermittent CAN timeouts). Clean with electrical contact cleaner.

4. 4

   Continuity Test

   Using a multimeter, perform a continuity test on the CAN-H and CAN-L wires end-to-end between the ACC and the ECM.

5. 5

   Repair Wiring

   If you find high resistance, an open circuit, or a short to ground/power, repair the damaged section of the wiring harness using proper weatherproof splices.

6. 6

   Reassemble

   Reconnect all modules securely. Apply dielectric grease to the weather seals (do not pack the pins directly).

7. 7

   Clear and Test

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) to clear the inactive fault codes. Start the tractor and operate the throttle and PTO to verify the ECM is successfully receiving the TSC1_ACCR torque commands and the code does not return.

8. 8

   Module / Software Update

   If the wiring is perfectly intact and voltages are correct, the ACC or ECM may have an internal CAN transceiver failure, or a software glitch. In this case, a dealer must flash the modules with the latest software or replace the faulty module.