Case IH 2388 – Transmission Control Unit (TCU) or Electronic Control Unit (ECU): 1st shaft speed sensor short to ground - Input shaft speed sensor

The control module has detected a short to ground in the electrical circuit of the transmission's input shaft speed sensor. Because the signal wire is shorted to ground, the controller cannot read the speed pulses, which can result in the transmission refusing to shift gears or being locked out of higher gears.

• Steiger T4B
• Steiger
• Quadtrac
• Steiger 350
• Steiger 400
• Steiger 435
• Steiger 450
• Steiger 500
• Steiger 535
• Steiger 550
• Steiger 600
• Quadtrac 350
• Quadtrac 400
• Quadtrac 435
• Quadtrac 450
• Quadtrac 500
• Quadtrac 535
• Quadtrac 550
• Quadtrac 600
• Magnum

1. 1

   Visually inspect connectors at the sensor and the ECU to ensure they are connected, undamaged, pins are in the correct position, and the fit is tight.

2. 2

   Perform a harness short test by disconnecting the sensor and testing the signal wire for continuity to ground. Continuity indicates a short in the wiring harness.

3. 3

   Test the internal resistance of the sensor itself. A known good transmission speed sensor typically measures around 3,000 ohms.

4. 4

   Use the Case IH Electronic Service Tool (EST) to monitor Sensor 1 outputs to see if a signal is generated during cranking or operation.

1. 1

   Locate the Sensor

   Locate the specific sensor monitoring the input shaft (Sensor 1).

2. 2

   Wiring Repair (If Applicable)

   If the continuity test revealed a short to ground in the harness, trace the harness back toward the ECU, locate the chafed or melted wire, and repair the damaged section.

3. 3

   Sensor Removal

   If the sensor failed the resistance test or is internally shorted, disconnect the electrical connector, remove the retaining bolt, and pull the sensor out of the transmission housing.

4. 4

   Spacer Transfer (CRITICAL)

   Remove the spacer from your old 1st shaft speed sensor and install it onto the new sensor to set the correct depth into the transmission housing.

5. 5

   Installation

   Insert the new sensor (with the correct spacer) into the housing, tighten the retaining bolt, and plug in the electrical connector.

6. 6

   Clear Codes

   Turn the key on and use the EST or the tractor's diagnostic display to clear the inactive fault code, then test operate the machine to ensure it shifts properly.