Case IH 521-00 - ITBV – ITBV: Service brake disagreement - pedal not pressed, tractor service brake pressure high.

The system is detecting high pneumatic or hydraulic pressure in the tractor's service brake circuit, but the brake pedal position switch/sensor is reporting that the pedal is not currently being pressed. This disagreement between the physical pedal position and the line pressure triggers the fault.

• MAGNUM AFS Connect
• Magnum series (e.g., 325 PowerDrive Stage V)
• Farmall series (e.g., 100C, 105U, 110C)
• Puma series
• Maxxum series

1. 1

   Verify the brake pedal switch correctly registers the 'released' position when the operator's foot is off the pedal.

2. 2

   Use a diagnostic tool to monitor live data from the air/hydraulic brake pressure sensor and compare it to a manual gauge to check for a skewed or stuck sensor.

3. 3

   Inspect the wiring harness connecting the ITBV, brake pressure sensor, and brake pedal switch for chafing, corrosion, or shorts to voltage/ground.

4. 4

   Verify if there is actual residual pneumatic or hydraulic pressure in the brake lines when the pedal is released to rule out mechanical binding (e.g., stuck solenoid valve or restricted return line).

1. 1

   Test and Replace the Brake Pedal Switch

   If the pedal switch does not change state when the pedal is pressed and released, replace the brake pedal switch.

2. 2

   Test and Replace the Brake Pressure Sensor

   If the brake pressure sensor is reporting false high pressure, relieve all system pressure safely, remove the faulty sensor, and install a new OEM pressure sensor.

3. 3

   Repair the Wiring Harness

   If diagnostic testing reveals a short or open circuit in the Air Brake Pressure Sensor Wire Harness, repair the damaged section or replace the harness entirely.

4. 4

   Replace the ITBV Module

   If the sensors, switches, and wiring all test perfectly, the ITBV Electronic Control Unit itself may have an internal fault and will need to be replaced and recalibrated.