Case IH 19401 – Engine Control Module (ECM) or Vehicle Control Module (VCM): Timeout of CAN-Transmit-Frame TxTC1, CAN frame Transmission Control 1

The Engine Control Module (ECM) or Vehicle Control Module (VCM) is expecting to receive the "Transmission Control 1" (TxTC1) data message from the transmission controller, but the message is not arriving within the programmed time limit (timeout).

• Tier 4b
• Magnum
• Maxxum
• Puma
• Optum
• Steiger
• N-Series Tractor Loader Backhoes / TLBs
• Wheel Loaders
• T6
• T7
• T8

1. 1

   Check for accompanying CAN bus timeout codes (e.g., VDC1, VEP1, or Bus Off errors) to determine if the entire network is down.

2. 2

   Inspect the CAN High and CAN Low twisted-pair wiring between the ECM/VCM and the TCU for chafing, pinch points, or melted insulation.

3. 3

   Check the plugs at the TCU and ECM for water ingress, bent pins, or corrosion.

4. 4

   Test CAN bus resistance across the CAN High and CAN Low pins at the diagnostic port with the battery disconnected (should be approximately 60 ohms).

5. 5

   Verify the Transmission Control Unit is receiving proper voltage and has a clean ground.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical shorts during testing.

2. 2

   Clean and Reseat Connectors

   Disconnect the main harness from the Transmission Control Unit and the ECM. Spray the contacts with electrical contact cleaner, ensure no pins are pushed back, and securely reconnect them.

3. 3

   Repair Wiring

   If continuity testing reveals an open or shorted CAN wire between the ECM and TCU, splice and repair the damaged section using proper weatherproof heat-shrink connectors.

4. 4

   Replace Terminating Resistors

   If the CAN bus resistance tested out of spec (e.g., 120 ohms instead of 60 ohms), locate and replace the faulty CAN terminating resistor on the network.

5. 5

   Replace the TCU

   If the wiring harness is intact, the CAN resistors are good, and the TCU has verified power and ground but still will not communicate, the TCU has likely suffered an internal hardware failure and must be replaced.

6. 6

   Clear Codes and Calibrate

   Reconnect the battery. Use a dealer-level diagnostic tool (such as Jaltest or Case IH Electronic Service Tool) to clear the 19401 fault code. If a new TCU was installed, flash the module with the correct machine software and perform any required transmission calibrations.