Massey Ferguson 4.X.B8 – Transmission Controller (TRANS1) / Autotronic 5: Issue With Intermediate Speed Sensor Values (TRANS1)

The transmission controller is detecting an illogical or missing signal from the intermediate speed sensor (TR23 or TR25). The system triggers this code when it detects no intermediate speed value while the actual forward travel speed is greater than 0, or when there is an impossible discrepancy between the engine speed, the intermediate speed, and the theoretical forward speed.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Perform a resistance test: Disconnect the sensor and measure resistance across its two pins. A healthy inductive speed sensor should read approximately 450 Ohms (+/- 20 Ohms) when stopped. An infinite reading indicates an internal open circuit.

2. 2

   Perform a voltage output test: With a multimeter connected, check for alternating voltage (AC) while the transmission gear is rotating.

3. 3

   Inspect the wiring harness between the sensor and the Autotronic 5 ECU. Look for backed-out pins, chafed wires causing a short to ground (0V) or power (+12V), or an open circuit.

4. 4

   Connect a diagnostic tool (Wintest or Jaltest) and monitor the intermediate speed sensor value in RPM while driving to see if the signal drops out intermittently.

1. 1

   Preparation

   Locate the intermediate speed sensor on the gearbox housing. If the sensor is located below the fluid level, partially drain the transmission oil into a clean container.

2. 2

   Removal

   Disconnect the electrical harness. Loosen the counter-nut (locknut) and unscrew the old sensor from the housing.

3. 3

   Installation & Air Gap Adjustment

   Apply a small amount of thread sealant (e.g., Loctite 5922) to the threads of the new sensor.

4. 4

   Install Sensor

   Carefully screw the new sensor in fully until it bottoms out against the internal gear.

5. 5

   Adjust Air Gap

   Unscrew the sensor by exactly ¾ of a turn to establish the correct air gap.

6. 6

   Secure Sensor

   Hold the sensor in place and tighten the counter-nut to approximately 6 Nm.

7. 7

   Reassembly

   Reconnect the electrical harness and refill the transmission fluid if any was drained.

8. 8

   System Reset

   Clear the fault codes. On some Autotronic 5 systems, a manual reset can be performed by moving the PowerControl lever to the neutral position, then pressing and releasing the clutch pedal. Test drive to verify the intermediate speed registers correctly.