Case IH 517761-03 - UCM – UCM: Electro-hydraulic backup steering pressure sensor voltage high

The system has detected that the voltage signal returning from the electro-hydraulic backup steering pressure sensor is exceeding the maximum expected threshold. This typically indicates a short to power in the sensor's signal wire, an open ground circuit, or an internal failure of the sensor itself.

• MAGNUM AFS Connect
• Magnum AFS Connect Series Tractors (180, 200, 220, 240, 250, 280, 310, 340, 380, and 400 Tier 4B / Stage V)
• Steiger AFS Connect tractors

1. 1

   Inspect the wiring harness leading from the UCM to the backup steering pressure sensor for chafed wires, pinched harnesses, or melted insulation that could cause a short to power.

2. 2

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

3. 3

   With the key ON (engine off), use a multimeter to verify that the sensor is receiving the correct reference voltage (usually 5V) and has a solid ground. An open ground wire will often cause a sensor to default to a voltage high state.

4. 4

   Check the signal wire from the sensor connector back to the UCM for continuity and ensure it is not shorted to a 12V power source.

5. 5

   If the wiring, reference voltage, and ground are all within specification, the sensor has likely failed internally and is outputting a high voltage.

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground to prevent electrical spikes during repair.

2. 2

   Locate the Sensor

   Locate the electro-hydraulic backup steering pressure sensor on the steering/hydraulic valve block.

3. 3

   Remove the Faulty Sensor

   Disconnect the electrical harness. Carefully unscrew the pressure sensor from the hydraulic block. Have a rag ready, as a small amount of hydraulic fluid may leak.

4. 4

   Install the New Sensor

   Thread the new OEM pressure sensor into the port and tighten to the manufacturer's torque specification.

5. 5

   Reconnect

   Plug the electrical connector back into the sensor, ensuring the locking tab clicks into place.

6. 6

   Clear Codes and Test

   Reconnect the battery, power on the tractor, and use the Electronic Service Tool (EST) or the AFS Pro display to clear the inactive 517761-03 fault code. Start the machine and test the steering system to ensure the code does not return.