Case IH 518083-04 - DEC – DEC: Park brake pressure sensor - voltage below normal or short to ground

The park brake pressure sensor is a variable resistance sensor that monitors the regulated hydraulic pressure in the parking brake release circuit. A 'voltage below normal' condition means the controller is receiving a signal voltage that has dropped below the acceptable operating range. This is typically caused by a short to ground in the sensor's internal circuitry, a short to ground in the wiring harness, or a completely failed sensor.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect series
• Case IH Steiger AFS Connect series
• Case IH Axial-Flow combines

1. 1

   Verify hydraulic pressure in the transmission/park brake circuit to ensure the issue is not mechanical (e.g., transmission pump or filter restriction).

2. 2

   Disconnect the sensor and use a multimeter to verify the controller is supplying a steady 5V reference to the sensor connector.

3. 3

   Test the signal wire between the sensor connector and the DEC for continuity and check for a short to ground.

4. 4

   Inspect the 3-cavity connector at the sensor for moisture, corrosion, or backed-out pins.

5. 5

   Check for cracked solder joints on the armrest circuit board, which can cause erratic voltage readings on some models.

1. 1

   Secure the Machine

   Park the machine on a level surface, turn off the engine, and securely chock the wheels. The park brake will engage when pressure is lost, but chocking is required for safety.

2. 2

   Locate the Sensor

   Locate the park brake pressure sensor, which is typically threaded into the transmission control valve block or the primary hydraulic power system manifold.

3. 3

   Disconnect Electronics

   Unplug the 3-cavity electrical connector from the sensor.

4. 4

   Remove the Sensor

   Clean the area around the sensor to prevent dirt from entering the hydraulic system. Use the appropriate wrench to unthread and remove the faulty pressure sensor. Have a rag ready to catch minor hydraulic oil seepage.

5. 5

   Install the New Sensor

   Lubricate the new sensor's O-ring/seal with clean hydraulic oil. Thread the new sensor into the port and tighten to the OEM torque specification.

6. 6

   Reassemble and Test

   Reconnect the electrical harness. Turn the key on, access the diagnostic monitor, and clear the inactive 518083-04 fault code. Start the tractor and cycle the park brake switch to confirm the brake releases and the code does not return.