Case IH 518583-04 - UCM – UCM: Brake Assisted Steering Pressure Sensor Voltage Below Normal, Or Shorted To Low Source

The control module is receiving a lower-than-expected voltage signal from the brake-assisted steering pressure sensor. This condition is typically caused by a short to ground in the sensor's wiring harness, a loss of the 5V reference voltage from the controller, or an internal failure of the sensor itself.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect Series
• Magnum Rowtrac
• Case IH Maxxum Series

1. 1

   Inspect the brake-assisted steering wiring harness (often routed near the rear axle and hydraulic valve blocks) for visible chafing, pinched wires, or corrosion at the connectors.

2. 2

   Disconnect the pressure sensor and turn the key to the ON position. Measure the reference voltage pin at the harness connector. The UCM should be supplying a steady 5V reference signal. If the voltage is 0V, trace the wire back to the UCM to find the open circuit or short to ground.

3. 3

   Verify that the ground pin has good continuity to the chassis/UCM ground. Check the signal return wire for a short to ground.

4. 4

   If the wiring harness is intact, the 5V reference is present, and the ground is good, the pressure sensor has failed internally and is pulling the signal voltage low.

1. 1

   Depressurize the System

   Park the tractor on a level surface, turn off the engine, and actuate the steering and brakes to relieve any residual hydraulic pressure in the system.

2. 2

   Locate the Sensor

   Locate the brake-assisted steering pressure sensor on the steering/brake hydraulic control valve block.

3. 3

   Disconnect the Harness

   Unplug the electrical connector from the sensor.

4. 4

   Remove the Sensor

   Unthread the faulty pressure sensor. Have a shop towel ready to catch any minor hydraulic fluid loss.

5. 5

   Install the New Sensor

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

6. 6

   Reconnect and Clear

   Reconnect the electrical harness. Turn the key on and use the AFS Pro display or the CNH Electronic Service Tool (EST) to clear the inactive 518583-04 fault code from the UCM.

7. 7

   Test

   Start the tractor and perform a test drive, executing tight headland turns to verify the brake-assisted steering engages properly without triggering a warning.