John Deere 524191.03 – CCU: Voltage At the Air Brake Solenoid Is High

The controller is detecting a higher-than-expected voltage on the circuit that controls the trailer air brake solenoid valve. This typically indicates a short to power in the wiring harness or an internal failure/short within the solenoid coil itself.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6100MC
• 6110MC
• 6090RC
• 6100RC
• 6110RC
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R

1. 1

   Power cycle the tractor to see if the code clears, which may indicate a transient voltage spike

2. 2

   Visually inspect the wiring harness from the Rear CCU to the air trailer brake solenoid valve for chafed insulation, pinched wires, or shorts to a 12V power source or chassis

3. 3

   Disconnect the electrical connector at the air brake solenoid and perform a voltage test on the signal wire with the key ON (brake not commanded) to check for an unexpected 12V presence (short to power)

4. 4

   Measure the coil resistance across the pins of the air brake solenoid to check for an internal dead short

1. 1

   Safeguard the Machine

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and remove the key. Chock the wheels.

2. 2

   Bleed Air Pressure

   Safely bleed the residual air pressure from the pneumatic brake system to prevent injury when removing the valve.

3. 3

   Locate the Solenoid

   Locate the air trailer brake valve block (typically mounted on the rear chassis near the trailer air couplings).

4. 4

   Wiring Repair (If Applicable)

   If the diagnostic checks revealed a short to power in the harness, trace the wire back to the CCU, splice in a repair wire, and seal it with marine-grade heat shrink.

5. 5

   Solenoid Replacement (If Applicable)

   Disconnect the electrical connector from the faulty solenoid. Remove the retaining screws/hardware holding the solenoid coil to the pneumatic valve body. Install the new air trailer brake solenoid and tighten the hardware to OEM torque specs. Reconnect the electrical harness.

6. 6

   Test

   Turn the tractor on and verify that the 524191.03 code has moved from 'Active' to 'Stored.' Clear the code and test the trailer air brakes to ensure proper engagement and disengagement.