Case IH 2159 (519173.04) - DEC – Transmission Control Unit (TCU): Synchro 2-4 Position Sensor - open circuit or short circuit to GND

An electrical failure in the circuit for the Synchro 2-4 Position Sensor, which monitors the position of the synchronizer sleeve/fork for the 2nd and 4th gears in the transmission. This indicates either a complete break in the electrical path (open circuit) or the sensor's signal/supply wire making unintended contact with the chassis/ground (short circuit to GND).

• MAXXUM T4E

1. 1

   Visually inspect the wiring harness leading to the transmission's Synchro 2-4 Position Sensor for chafing, pinched wires, or breaks.

2. 2

   Disconnect the sensor and inspect the pins for corrosion, pushed-back terminals, or moisture ingress.

3. 3

   Use a multimeter to test the harness wires from the sensor connector back to the TCU for continuity to rule out a broken wire (open circuit).

4. 4

   Test the signal and power supply wires for continuity to the chassis ground. If continuity is found where there should be voltage, a short to ground is present.

1. 1

   Locate sensor

   Locate the Synchro 2-4 Position Sensor on the transmission housing.

2. 2

   Disconnect connector

   Disconnect the electrical connector from the sensor.

3. 3

   Repair wiring

   If the diagnostic checks revealed damaged wiring (a break or a short to the chassis), repair the affected section of the wiring harness or replace the connector pigtail.

4. 4

   Remove sensor

   If the wiring harness tests perfectly, the fault is internal to the sensor. Remove the mounting hardware securing the sensor and extract it from the transmission.

5. 5

   Install new sensor

   Install the new position sensor and torque to OEM specifications.

6. 6

   Reconnect wiring

   Reconnect the wiring harness.

7. 7

   Clear codes and test

   Clear the fault codes via the diagnostic menu or service tool and perform a test drive, shifting through gears 2 and 4 to verify the repair.