Case IH 19889 (DTC 45E1) - ECU – Engine Control Unit (ECU) / Vehicle Control Module (VCM) / Heater Control Unit (HCU): Vehicle speed CAN message not received

The control module expects to see a continuous broadcast of the machine's ground speed over the Controller Area Network (CAN) bus, but that specific data packet is missing or timing out.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• N-Series Tractor Loader Backhoes (TLBs)

1. 1

   Observe the cab monitor (e.g., AFS Pro 700) to see if the machine is registering ground speed while moving. If the display shows '0' while moving, the speed sensor itself or its direct wiring is likely the culprit.

2. 2

   Look for other CAN bus communication errors (e.g., SPN 19887 or 19888). If multiple modules are reporting missing messages, the entire CAN network may be down due to a short or bad terminating resistor.

3. 3

   Visually inspect the wiring harness running from the transmission/ground speed sensor to the main cab controller and the Engine ECU/VCM for chafing, rodent damage, or pinched wires.

4. 4

   Disconnect the ECU and speed sensor connectors to check for pushed-back pins, corrosion, or moisture intrusion.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical spikes during testing.

2. 2

   Test CAN Continuity

   Using a multimeter, measure the resistance across the CAN High and CAN Low pins at the diagnostic port. A healthy CAN bus should read approximately 60 ohms. If it reads 120 ohms, a terminating resistor or a section of the bus is broken.

3. 3

   Repair Wiring

   If a break or short to ground is found in the CAN lines between the speed sensor/transmission controller and the Engine ECU, splice and seal the damaged wires using OEM-approved heat-shrink connectors.

4. 4

   Clean Connections

   Apply dielectric grease to the ECU and sensor connectors and securely reconnect them, ensuring no pins are bent.

5. 5

   Replace Sensor

   If the wiring is fully intact and the CAN bus is healthy but the speed sensor is internally shorted or dead, remove the retaining bolt, pull the old speed sensor from the transmission/housing, and install a new one.

6. 6

   Clear and Test

   Reconnect the battery, turn the key on, clear the inactive fault codes via the diagnostic menu, and test drive the machine to ensure the ECU successfully receives the speed message and the code does not return.