Case IH 12811 – Trailer Brake Controller (iTBV): Trailer Brake Controller Service Brake Sensor Voltage High

Indicates a permanent high voltage level at PWM signal 1 (the brake pedal demand sensor) or indicates that the sensor is completely disconnected.

• MAXXUM T4E
• Farmall 40-45-50
• Farmall 105U
• Farmall 110U
• Farmall 85A-120U
• Maxxum 100-150
• Puma
• Magnum
• MXM
• MXU

1. 1

   Check the physical connection at the brake pedal demand sensor to ensure the plug is not simply disconnected, which defaults to a high-level/open circuit fault.

2. 2

   Inspect the brake sensor 1 power supply for a short to power or a short to ground.

3. 3

   Verify the CAN communication with the Trailer Brake Controller (iTBV) to ensure it is communicating properly with the tractor's main network.

4. 4

   Use a multimeter to verify the actual voltage on the PWM signal 1 wire at the sensor harness to confirm if it is stuck high.

1. 1

   Locate sensor

   Locate the service brake sensor (brake pedal demand sensor) near the brake pedal assembly or trailer brake supply lines.

2. 2

   Inspect wiring harness

   Disconnect the sensor's wiring harness and inspect the pins for corrosion, pushed-out pins, or moisture.

3. 3

   Test wiring harness

   Test the wiring harness back to the Trailer Brake Controller for continuity and ensure there is no short to power on the signal wire.

4. 4

   Diagnose sensor failure

   If the wiring harness tests good and the sensor is receiving the correct reference voltage and ground, the sensor itself has failed internally, causing the permanent high PWM signal.

5. 5

   Replace sensor

   Remove the defective service brake sensor and install the replacement part.

6. 6

   Verify repair

   Reconnect the wiring harness, clear the fault codes from the Trailer Brake Controller, and cycle the brake pedal to verify the PWM signal is now reading correctly.