New Holland NH 2085 – Transmission Control Unit (TCU) / XCM (Multi-function Control Module) / ADIC: Synchro 4 solenoid open circuit

The transmission control system has detected a break in the electrical circuit (lack of continuity or infinite resistance) leading to the solenoid responsible for engaging the 4th synchronizer in the transmission. Because the circuit is open, the controller cannot actuate the solenoid, which will likely result in a loss of the associated gears or a transmission default/limp mode.

• T5 Series
• TM Series
• TM 175
• TN Series

1. 1

   Inspect the wiring harness running from the Transmission Control Unit (XCM) to the transmission valve block for chafed wires, breaks, or rodent damage

2. 2

   Disconnect the electrical connector at the Synchro 4 solenoid and inspect the pins for corrosion, moisture, or pushed-out terminals

3. 3

   Using a digital multimeter, measure the resistance across the pins of the Synchro 4 solenoid coil (an 'OL' or infinite ohms reading indicates a broken internal coil)

4. 4

   If the solenoid tests within normal resistance specifications, test the continuity of the wiring harness between the solenoid connector and the transmission controller to locate the break in the wire

1. 1

   Safety First

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and disconnect the negative battery cable.

2. 2

   Locate the Valve Block

   Locate the transmission control valve block, which is typically mounted on the side or top of the transmission housing.

3. 3

   Identify the Solenoid

   Using your specific model's service manual, identify which of the solenoids on the block is the Synchro 4 solenoid.

4. 4

   Disconnect Wiring

   Unplug the electrical harness connector from the faulty solenoid.

5. 5

   Remove the Solenoid

   Depending on the valve block design, either remove the retaining nut at the end of the stem to slide the electromagnetic coil off the valve cartridge, or unbolt the entire solenoid valve assembly from the manifold. (Be prepared to catch a small amount of hydraulic fluid if removing the hydraulic cartridge).

6. 6

   Install the New Part

   Slide the new solenoid coil onto the stem and tighten the retaining nut, or install the new valve assembly using fresh O-rings.

7. 7

   Reconnect

   Plug the electrical connector back in and reconnect the battery.

8. 8

   Clear and Calibrate

   Clear the NH 2085 fault code using a diagnostic tool. You may need to perform a transmission clutch/synchro auto-calibration procedure before returning the tractor to field service.