Massey Ferguson 4.01.91 – Transmission Control Module (TCU) / TRANS1: Issue With Speed Sensor Values (TRANS1)

This indicates that the transmission control system is receiving an erratic, missing, or out-of-range signal from the transmission-mounted speed sensor. This can result in erratic speedometer readings, loss of cruise control, or the transmission disengaging ranges/shifting poorly.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 5400 series
• 6400 series
• 6600 series

1. 1

   Visually inspect the sensor, pins, and connector for signs of corrosion, melting, or physical damage

2. 2

   Perform a resistance test by disconnecting the sensor and measuring across the two pins at ambient temperature (should read 450 Ohms +/- 20 Ohms)

3. 3

   Check for an alternating voltage (AC) signal from the sensor when the gear is turning

4. 4

   Test the wiring harness for continuity, insulation integrity, short-circuits to ground (-), and short-circuits to power (+)

5. 5

   Use Massey Ferguson's Wintest or EDT diagnostics software to monitor active sensor values and confirm signal drop-off

1. 1

   Locate the Sensor

   Identify the faulty speed sensor on the transmission housing (often located on the top or side of the transmission case/rear axle).

2. 2

   Disconnect Wiring

   Carefully unplug the 2-pin electrical connector from the sensor.

3. 3

   Remove the Sensor

   Unbolt or unscrew the sensor from the transmission housing. Warning: The sensor sits in hydraulic fluid. Be prepared to quickly plug the hole to minimize fluid loss when you pull it out.

4. 4

   Install the New Sensor

   Lubricate the O-rings on the new sensor with clean transmission fluid and insert it into the housing. Secure it with the retaining bolt.

5. 5

   Reconnect and Clear

   Reconnect the wiring harness. Use your diagnostic tool to clear the 04.02.91 fault code and test drive the tractor to verify the speedometer and shifting are functioning normally.