Massey Ferguson T4186 – TRANS (Transmission Control Module / Autotronic 4 / Autotronic 5 / ML260): Transmission High Pressure Sensor Signal Voltage Issue DYNA VT (TRANS)

The transmission controller is receiving an erratic, out-of-range, or illogical voltage signal from the primary high-pressure sensor (Sensor X9) that monitors the hydrostatic drive circuit of the continuously variable transmission.

• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• Interim Tier 4 (2012-2015)
• 6614
• 6615
• 6616
• 6713S-6718S
• 7714-7726S
• 8650
• 8660
• 8670
• 8680
• 8690
• 8727S-8740S

1. 1

   Verify the X9 high-pressure sensor is receiving a steady 8.5V reference voltage supply from the transmission controller.

2. 2

   Inspect the wiring harness and connector at sensor X9 for chafing, moisture ingress, or loose pins causing voltage drops.

3. 3

   Use a mechanical test gauge at transmission test port M9 (High Pressure / PH) to verify the transmission is generating correct pressure, ruling out hydrostatic pump/motor failure.

1. 1

   Depressurize the System

   Ensure the tractor is off, the transmission is cooled (oil temperature should ideally be between 35°C and 45°C for testing/service), and hydraulic pressure is relieved.

2. 2

   Replace the Sensor

   Locate Sensor X9 on the transmission block. Disconnect the electrical harness, unthread the faulty sensor, and install the replacement part.

3. 3

   Perform Mandatory Calibration

   According to the ML260 Dyna-VT service manual, a transmission calibration must be carried out systematically after changing the transmission high-pressure sensor.

4. 4

   Calibration Prerequisites

   The hand brake must be applied or ParkLock engaged. The Power Control lever must be in the neutral position. The High/Low (Hare/Tortoise) speed range must be in neutral (symbols flashing alternately on the screen). Note: This calibration must be performed immediately after a range calibration has been completed.