Massey Ferguson 04.00.B8 – Transmission Control Unit (TCU) / TRANS1: Issue With Intermediate Speed Sensor Values (TRANS1)

This fault code indicates that the transmission control system is receiving an abnormal, missing, or implausible signal from the intermediate speed sensor (an inductive sensor). The system flags this error when the logic detects a mismatch—such as no intermediate speed being detected while the current forward speed or engine speed is greater than zero, or an erratic signal that falls outside expected RPM parameters.

• 7724S
• 5712SL
• 7722
• 7722S
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7726S
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724

1. 1

   Inspect the wiring harness and connector at the sensor for backed-out pins, corrosion, or broken wires.

2. 2

   With the tractor stopped and turned off, disconnect the sensor and measure the resistance across its two pins (Pin 1: Signal, Pin 2: Earth). A healthy inductive speed sensor should read approximately 450 Ohms (± 20 Ohms). If it reads an open circuit, the sensor has failed internally.

3. 3

   Back-probe the sensor while the transmission gear is rotating. The sensor should generate an Alternating Voltage (AC). If resistance is good but there is no AC voltage, the air gap may be incorrect.

1. 1

   Locate the Sensor

   Locate the intermediate speed sensor on the transmission housing (often positioned above the differential ring gear or intermediate shaft).

2. 2

   Removal

   Disconnect the electrical harness, loosen the counter-nut, and unscrew the faulty sensor from the housing.

3. 3

   Preparation

   Apply a small amount of thread sealant (such as Loctite 5922) to the threads of the new sensor.

4. 4

   Air Gap Adjustment

   Carefully screw the new sensor in fully until it gently bottoms out (touches) the internal gear. Unscrew the sensor by exactly ¾ of a turn to establish the correct air gap.

5. 5

   Secure

   Hold the sensor firmly in this position and tighten the counter-nut to approximately 6 Nm.

6. 6

   Reassembly & Reset

   Reconnect the electrical harness. Clear the fault codes using Wintest/diagnostic software, or perform a system reset (on some models, this is done by moving the PowerControl lever to the neutral position and then pressing and releasing the clutch pedal).