Massey Ferguson 04.01.89 – Transmission Control Module (TRANS): Transmission Oil Temperature Signal Issue

The electronic control system is receiving an erratic, out-of-range, or missing electrical signal from the transmission hydraulic oil temperature sensor (often designated in Massey Ferguson schematics as sensor X19).

• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S
• Tier 4 (2015-2021)
• 7700 Series
• 7700S Series
• 7600 Series
• 8600 Series
• 6400 Series
• 5400 Series

1. 1

   Check transmission/hydraulic oil level and condition to ensure it is not degraded or contaminated, which can cause erratic readings.

2. 2

   Inspect the transmission oil cooler and radiator fins to ensure they are completely clean and free of hay, dust, or debris.

3. 3

   Locate the transmission oil temperature sensor (X19) on the transmission housing and inspect the wiring harness and electrical connector for corrosion, broken wires, or loose pins.

4. 4

   Test the sensor using a multimeter to check resistance and voltage, looking for a short to ground, an open circuit, or a short to power.

5. 5

   Check for related concurrent codes (e.g., transmission filter blockage warning) that could indicate a flow restriction rather than an electrical failure.

1. 1

   Prepare machine

   Park the tractor on a flat, level surface, engage the parking brake, and turn off the engine. Allow the transmission fluid to cool completely to avoid burns.

2. 2

   Locate sensor

   Locate the transmission hydraulic oil temperature sensor (X19) on the side of the transmission housing.

3. 3

   Clean area

   Thoroughly clean the area around the sensor to prevent dirt or debris from falling into the transmission when the sensor is removed.

4. 4

   Disconnect connector

   Disconnect the electrical connector from the sensor.

5. 5

   Place catch pan

   Place a catch pan underneath the sensor area to catch any hydraulic fluid that may weep out.

6. 6

   Remove sensor

   Unscrew and remove the faulty temperature sensor.

7. 7

   Install new sensor

   Install the new OEM temperature sensor (ensure any required O-ring is in place) and tighten it to the manufacturer's specified torque.

8. 8

   Reconnect connector

   Reconnect the electrical connector securely.

9. 9

   Check fluid level

   Check the transmission fluid level and top up any fluid lost during the swap.

10. 10

    Test operation

    Turn on the tractor, clear the fault codes via the dash or a diagnostic tool, and test operate the machine to ensure the transmission temperature registers correctly and the code does not return.