Case IH 19848 – Engine Control Module (ECM / ECU): CAN timeout error for TSC1 of Gearbox/Vehicle management torque and/or speed request to ECM

The Engine Control Module (ECM/ECU) has lost communication over the CAN bus with the Transmission Control Unit (TCU) or Vehicle Control Module (VCM). Specifically, the ECM has stopped receiving the "TSC1" (Torque/Speed Control 1) message, which is used to request specific engine speed or torque limits.

• Tier 4b
• Case IH Puma
• Case IH Optum
• Case IH Magnum
• CNH N-Series Loaders
• CNH Tractor Loader Backhoes (TLBs)

1. 1

   Check for multiple codes using the Case IH Electronic Service Tool (EST) to see if other CAN timeout codes (e.g., 19849, 19850, 19851) are present, indicating the entire CAN bus network is down.

2. 2

   Measure CAN bus resistance across the CAN High and CAN Low pins at the diagnostic port with the battery disconnected. It should read exactly 60 ohms. 120 ohms indicates a missing terminating resistor or broken wire; an open reading indicates a severed wire or disconnected harness.

3. 3

   Check CAN voltages with the key ON. CAN High (typically Yellow wire) should be 2.5V to 2.7V, and CAN Low (typically Green wire) should be 2.3V to 2.5V.

4. 4

   Verify module power and ground to ensure the Transmission Control Unit (TCU) or Vehicle Control Module (VCM) is receiving proper 12V power and ground.

1. 1

   Disconnect Battery Power

   Always disconnect the battery before repairing CAN bus wiring to prevent module damage.

2. 2

   Inspect Harnesses

   Trace the CAN bus wiring harness between the ECM and the Transmission/Vehicle controller. Look for areas where the harness may have rubbed under the cab or near pivot points.

3. 3

   Clean Connectors

   Disconnect the main harness connectors at the ECM and the TCU/VCM. Inspect for pushed-out pins, corrosion, or moisture. Clean the contacts with electrical contact cleaner and ensure a tight terminal fitment.

4. 4

   Repair Wiring/Resistors

   If a broken wire is found, use a CAN bus repair kit to splice the connection. If the resistance test showed 120 ohms, locate and replace the faulty/missing 120-ohm terminating resistor.

5. 5

   Module Software/Replacement

   If the wiring is perfectly intact, terminating resistors are good, and the TCU/VCM has power but is still not communicating, the transmitting module itself may have failed or require a software re-flash via the Case IH EST.

6. 6

   Clear Codes and Test

   Reconnect the battery, clear the fault codes using the EST, and test drive the machine (specifically testing shifting and PTO engagement) to verify the TSC1 message is successfully reaching the ECM.