Massey Ferguson T4156 – Transmission Control Module (TRANS / TCU): Transmission filter blockage switch Signal error

An electrical or signal plausibility issue with the sensor that monitors the transmission hydraulic oil filter for blockages (Sensor X20). The controller is receiving an invalid, missing, or out-of-range electrical signal from this switch.

• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 7615
• 7620
• 7616
• 7618
• 7619
• 7626
• 7624
• 8670
• 8690

1. 1

   Inspect Sensor X20 wiring harness and connector on the transmission filter housing for corrosion, backed-out pins, or physical damage

2. 2

   Check transmission hydraulic oil quality for heavy pollution or degradation

3. 3

   Inspect the high-pressure transmission oil filter element for severe clogging

4. 4

   Test the X20 switch with a multimeter for continuity and resistance to check for internal failure (shorted or open circuit)

1. 1

   Clean the Connection

   Disconnect the harness from the X20 transmission filter blockage switch. Clean the contacts with electrical contact cleaner and ensure a tight fit. Re-test the machine to see if the code clears.

2. 2

   Repair Wiring

   If any wiring between the X20 sensor and the Transmission Control Module is damaged, splice and repair the wires using weather-sealed connectors.

3. 3

   Replace the Sensor

   If the wiring is intact and the connector is clean but the signal error persists, the X20 switch has failed internally. Unthread the old sensor from the filter housing and install a new OEM replacement switch.

4. 4

   Service the Filter

   If the tractor is near its service interval, or if the oil appears polluted, drain the transmission fluid, replace the transmission filter element, and refill with fresh, approved transmission hydraulic fluid.

5. 5

   Clear Codes

   Use a diagnostic tool to clear the T4156 code from the Transmission Control Module and test-drive the tractor to verify the repair.