John Deere 524191.02 – CCU: Brake Pedal Has Been Pressed But The Air Brake System Pressure Did Not Drop

When the operator presses the brake pedal, the tractor's control system commands the air brake system solenoid valve to actuate, which should result in a measurable pressure drop in the air brake circuit (typically to apply trailer brakes). The controller monitors this via an air brake pressure sensor. If the pedal is pressed but the sensor does not register the expected pressure drop, this code is triggered. It indicates a potential blockage in the pneumatic lines, a stuck solenoid valve, a faulty pressure sensor, or a wiring harness issue.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6115R
• 6125R
• 6135R
• 6140R
• 6150R
• 6230R
• 6250R
• 6090MC
• 6090RC
• 6100MC
• 6100RC
• 6110MC
• 6110RC
• 5075M
• 5085M
• 5090M
• 5090R
• 5100M
• 5100R

1. 1

   Check the air brake lines for kinks, pinched hoses, or blockages. In cold weather, check for frozen condensation in the air lines or valves.

2. 2

   Ensure the left and right brake pedal position sensors are functioning correctly and not sticking, as the CCU relies on these to know when the pedal is pressed.

3. 3

   Locate the air brake pressure sensor. Check the wiring harness and connector for corrosion, backed-out pins, or damage. Use a multimeter to verify the sensor is receiving a 5-volt reference from the CCU.

4. 4

   Check the air brake system solenoid valve. Verify the resistance of the solenoid coil and ensure it actuates when 12V is applied.

1. 1

   Depressurize the System

   Park the tractor on a level surface, engage the park brake, and turn off the engine. Pump the brake pedals or use the air tank drain valve to safely relieve all pneumatic pressure from the air brake system.

2. 2

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shorts and to reset the CCU during the repair.

3. 3

   Replace the Faulty Component

   If the pressure sensor is faulty: Disconnect the electrical harness from the sensor. Unthread the sensor from the air brake valve block/manifold. Install the new sensor with a new O-ring (typically 11.30 x 2.20 mm). Torque to OEM specifications. If the solenoid valve is stuck: Disconnect the solenoid harness. Remove the retaining screws or nut holding the solenoid coil/valve assembly to the pneumatic block. Clean the mounting surface and install the replacement valve.

4. 4

   Reassemble and Repressurize

   Reconnect the electrical connectors and the negative battery cable. Start the tractor and allow the air compressor to build system pressure.

5. 5

   Test Operation

   Press the brake pedal while monitoring the air brake pressure on the tractor's Command Center display (or via John Deere Service ADVISOR). Verify that the pressure drops appropriately when the pedal is applied.

6. 6

   Clear Codes

   Clear the inactive 524191.02 fault code from the CCU memory.