Case IH 15237 – MTA CCM & APH: Vehicle speed sensor message (from TCU) communication lost

CAN bus communication failure where the cab controller or display is no longer receiving the vehicle speed data broadcasted by the Transmission Control Unit (TCU).

• Steiger T4B
• Farmall 40
• Farmall 45
• Farmall 50
• Farmall 115U Efficient Power
• Farmall 95U Pro EP
• Farmall 105U Pro EP
• Farmall 115U Pro EP

1. 1

   Check for other codes to determine if the TCU is completely offline or if only the speed sensor message is missing.

2. 2

   Verify the Transmission Control Unit (TCU) is receiving proper operating voltage and has a clean ground.

3. 3

   Inspect the CAN communication wiring between the TCU and the Cab Control Module for continuity, shorts, or high resistance.

4. 4

   Inspect the transmission output speed sensor and its wiring harness leading to the TCU.

1. 1

   Locate modules

   Locate the Transmission Control Unit (TCU) and the Cab Control Module (CCM).

2. 2

   Inspect wiring harnesses

   Disconnect the wiring harnesses at both modules and inspect the pins for corrosion, moisture, or backed-out terminals. Clean or repair as necessary.

3. 3

   Test CAN bus wiring

   Test the CAN bus wiring with a multimeter to ensure proper resistance (typically 60 ohms across the network) and check for shorts to ground or power.

4. 4

   Inspect Vehicle Speed Sensor (VSS)

   Inspect the physical Vehicle Speed Sensor (VSS) on the transmission housing. Remove the sensor, clean any metallic debris from the magnetic pickup, and verify the sensor's resistance/signal output.

5. 5

   Repair or replace components

   Repair any damaged wiring harnesses or replace the speed sensor if it is faulty.

6. 6

   Test and verify

   Reconnect all modules, clear the fault codes, and test drive the tractor to verify the vehicle speed registers on the cab display. If the wiring and sensor are intact but the message is still lost, the TCU may require replacement or dealer reprogramming.