Massey Ferguson T4158 – TRANS: Possible Transmission Slippage Detected DYNA VT (TRANS)

The transmission slip monitor has detected that the transmission output speed indicates over 30% slippage compared to the expected value given the current engine speed and gear ratio. This means the transmission output shaft is spinning significantly slower than the input parameters dictate, indicating either a genuine mechanical slip within the continuously variable transmission (CVT) or a false reading from a speed sensor.

• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 7615
• 7620
• 7616
• 7618
• 7619
• 7626
• 7624
• 6614
• 6615
• 6616
• 6713 S
• 6714 S
• 6715 S
• 6716 S
• 6718 S
• 7485
• 7490
• 7495
• 7499
• 7715 through 7726
• 7S.145 through 7S.210
• 8650
• 8670
• 8690
• 8727
• 8730
• 8740

1. 1

   Check Transmission Fluid: Verify the transmission oil level and condition. Low fluid or degraded oil can cause genuine slippage or pressure drops.

2. 2

   Check for Filter Blockages: Look for accompanying fault codes like T4150 (Transmission Filter Blocked) or T4156/T4172 (Transmission Filter Blockage Sensor Issue). A starved hydrostatic unit will slip.

3. 3

   Test Transmission Speed Sensors: The controller calculates slippage by comparing the engine/input speed to the output speed. Check for accompanying codes like T4182 (Transmission Speed Sensors Issue) or T4183 (Issue With One Of The Transmission Speed/Direction Sensors). A failing inductive speed sensor will report a false drop in RPMs, triggering the T4158 code.

4. 4

   Check Transmission Oil Temperature: Ensure the transmission isn't overheating (Codes T4151, T4152, T4153), which thins the oil and causes hydrostatic slip.

5. 5

   Perform a Transmission Calibration: Recalibrate the Dyna-VT transmission using the tractor's command center display or dealer diagnostic tool to ensure the controller's reference curves are accurate.

1. 1

   Fluid and Filter Service

   If the fluid is low, burnt, or the filters are clogged, drain the transmission oil. Replace the main hydraulic/transmission oil filters and refill with the OEM-specified transmission fluid.

2. 2

   Sensor Replacement

   If diagnostic tests reveal erratic readings from the transmission output speed sensor or flywheel speed sensor, locate the faulty inductive sensor on the transmission housing. Disconnect the wiring harness, unthread the old sensor, and install the new OEM sensor. Clear the fault codes and test drive.

3. 3

   Limp Mode Reset

   The tractor may have engaged "Limp Home Mode" (Code T4159) to protect the transmission. Clear all codes via the diagnostic port after replacing sensors or filters.

4. 4

   Internal Transmission Repair

   If the sensors are reading correctly, the fluid is full, and the transmission still exhibits >30% slippage, the Dyna-VT (Vario) hydrostatic unit or internal clutch packs have mechanically failed. This requires splitting the tractor, removing the transmission module, and either rebuilding the hydrostatic pump/motor assembly or installing a remanufactured Dyna-VT transmission unit.