Case IH 2624 – Transmission Control Unit (TCU): Hydrostatic unit speed sensor (N_Hyd2) shorted to ground

The fault code indicates an error with the Hydrostatic unit speed sensor (N_Hyd2), specifically that its circuit is shorted to ground. This means the sensor's signal wire or internal circuitry has an unintended direct connection to the chassis ground (0V), preventing the controller from receiving the correct frequency or voltage signal generated by the spinning reluctor ring/gear.

• Steiger T4B
• Farmall 115U Pro EP
• Magnum 7220
• Magnum 8930
• Magnum 8940
• Magnum 8950

1. 1

   Visual Inspection: Ensure the sensor is securely plugged in and check the wiring harness for visible damage, chafing, or cuts that could cause a short to ground.

2. 2

   Continuity Test: Disconnect the sensor harness. Using a multimeter, test the harness pins for continuity to ground to determine if the short is in the wiring harness itself or internal to the sensor.

3. 3

   Module Isolation: If the harness is shorted, disconnect the harness at the Transmission Control Unit (TCU) and retest. If the short disappears, the issue is within the module; if it remains, the wiring harness is pinched or damaged.

1. 1

   Prepare machine

   Park the machine on a level surface, turn off the engine, and allow the hydraulic oil and engine coolant to cool down.

2. 2

   Disconnect battery

   Before working on the electrical system, disconnect the battery terminals to prevent damage or accidental shorting.

3. 3

   Locate sensor

   Locate the N_Hyd2 hydrostatic speed sensor on the transmission housing.

4. 4

   Unplug connector

   Unplug the electrical connector from the sensor.

5. 5

   Remove hardware

   Remove the mounting hardware securing the sensor or its bracket (often a 12-point flange bolt or M10 hex bolt).

6. 6

   Remove sensor

   Remove the faulty sensor and wipe the mounting port clean.

7. 7

   Install new sensor

   Install the replacement speed sensor and tighten the mounting bolt.

8. 8

   Reconnect harness

   Reconnect the electrical harness securely.

9. 9

   Reconnect battery

   Reconnect the battery terminals (positive first, then negative).