Iveco 101 – Transmission Control Unit (TCU): Speed error on both speed sensors (1 + 2)

The transmission control system has detected an abnormal, missing, or implausible signal from both the primary output speed sensor (impulse sensor) and the secondary speed sensor (often the Kitas/tachograph sensor) simultaneously. Without these signals, the transmission cannot determine the output shaft speed, which is critical for automated gear shifting.

• Stralis
• Trakker
• EuroCargo
• Buses and coaches

1. 1

   Inspect the wiring harness and connectors at the tail end of the transmission for physical damage, corrosion, or loose connections.

2. 2

   Test the wiring harness connector to the speed sensor for a positive voltage supply (typically 8V–10V, or up to 24V on certain pins).

3. 3

   Perform a cyclic continuity test from the transmission actuator wiring harness connector directly to the speed sensor connector to rule out a broken wire.

4. 4

   Use a diagnostic tool to see if there are individual sensor errors (e.g., code 100 for output speed signal 2) or CAN communication faults.

5. 5

   Verify if the speedometer/tachograph is also malfunctioning, as one of the signals is tied to the tachograph (Kitas sensor).

1. 1

   Locate the Sensors

   Safely secure the vehicle and locate the speed sensors mounted on the output shaft housing at the rear of the EuroTronic gearbox.

2. 2

   Disconnect Wiring

   Unplug the electrical connector from the speed sensor.

3. 3

   Remove the Sensor

   Unscrew the retaining ring nut or mounting bolt securing the sensor and pull the impulse sensor (and Kitas sensor, if replacing both) out of the transmission housing.

4. 4

   Install the New Sensor

   Insert the new speed sensor(s) and tighten to the manufacturer's specified torque. Caution: Over-torquing can affect the sensor's internal clearance and cause electronic noise or premature failure.

5. 5

   Reconnect Wiring

   Reconnect the electrical connector. The manual strictly notes that the connector must be fitted so that it is strain-relieved.

6. 6

   Parameterization

   If the Kitas (tachograph) sensor is replaced, the new sensor must be parameterized (taught-in) using a diagnostic tool. If this is not done, the speedometer and tachograph functions will no longer be available.

7. 7

   Clear Codes

   Clear the fault codes from the TCU and test drive the vehicle to confirm the output speed signal is restored.