Case IH tB5 – Power Control Unit (PCU) / Transmission Controller: CAN VE Message (Speed Set point), Data Incorrect

Communication error on the Vehicle CAN (Controller Area Network) bus where the engine speed setpoint data being broadcasted is invalid, corrupted, or incorrect.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Check for other CAN-related codes (such as tB4, tB6, tCA, or tCB) which might indicate a broader CAN bus failure, such as a short to ground or short to a high power source.

2. 2

   Inspect the wiring harness and connectors between the Engine Control Unit (ECU), the throttle potentiometer/speed sensor, and the PCU for chafing, corrosion, or backed-out pins.

3. 3

   Power OFF the machine and disconnect the battery. Disconnect the connectors at both ends of the CAN circuit to prevent false readings. Set a multimeter to measure resistance (ohms) and check the CAN bus lines for continuity, open circuits, or shorts to the chassis ground.

4. 4

   Test the throttle potentiometer and engine speed sensor to ensure they are sending the correct base voltage/resistance values to the ECU before the data is converted into a CAN message.

1. 1

   Disconnect battery

   Disconnect the battery to ensure safety and protect the microprocessors.

2. 2

   Clean connector pins

   Clean any corroded connector pins at the PCU and ECU with electrical contact cleaner and ensure they are seated tightly.

3. 3

   Repair or replace wiring harness

   Repair or replace any damaged sections of the CAN bus wiring harness identified during the resistance testing.

4. 4

   Replace sensor

   If the wiring is intact but the speed setpoint data is still incorrect, replace the faulty throttle potentiometer or engine speed sensor.

5. 5

   Reconnect battery

   Reconnect the battery and turn the key switch to the "ON" position.

6. 6

   Perform calibration

   A mechanical or electrical repair (especially replacing a potentiometer or microprocessor) requires a Transmission/EDC Calibration. Enter the H-Menu, set the engine speed to 1200 ERPM, and run the H1 Clutch and Synchroniser calibration until "END" displays.

7. 7

   Clear fault codes and test

   Clear the fault codes and test the tractor's operation to verify the repair.