Massey Ferguson 4.01.85 – Transmission Controller / Autotronic Box (TRANS or TRANS1): Issue With Signal From Transmission Mounted Engine Speed Sensor (TRANS) / Issue With Speed Sensor Values (TRANS1)

The controller is receiving an erratic, out-of-range, or missing signal from the inductive speed sensor mounted on the transmission, which monitors the engine/input shaft speed.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• 5400 Series
• 6400 Series
• 6600 Series
• 7600 Series

1. 1

   Use Massey Ferguson Wintest software to monitor live active and requested values of the engine/transmission speed to confirm the sensor is dropping the signal

2. 2

   Check the sensor socket on the tractor harness with a multimeter to ensure it is receiving the proper reference voltage (typically 12V)

3. 3

   Inspect the wiring harness for damage, corrosion, or chafing, ensuring all plugs on the Autotronic box have very clean and tight connections

4. 4

   Verify that all transmission and sensor-related fuses are intact

1. 1

   Locate the Sensor

   The sensor is threaded into the side of the transmission housing. Note: Depending on the specific tractor model (e.g., MF 6499), access can be extremely tight and may require removing the rear tire to safely reach the sensor.

2. 2

   Disconnect the Battery

   Always disconnect the battery before working on transmission electronics to prevent short circuits.

3. 3

   Remove the Connector

   Unplug the electrical pigtail/connector from the sensor.

4. 4

   Remove the Sensor

   Unbolt or unthread the sensor from the transmission housing. Be prepared for seized bolts if the tractor has been exposed to harsh elements for years.

5. 5

   Install the New Sensor

   Thread the new inductive sensor into the housing.

6. 6

   Reconnect

   Plug the electrical connector back in and ensure the protective sheath is intact.

7. 7

   Reassembly & Clearing Codes

   Reinstall the tire (if removed), reconnect the battery, and use the diagnostic tool to clear the 04.01.85 fault code from the TRANS1 module.