John Deere 524191.04 – CCU: Voltage At the Air Brake Solenoid Is Low

The control module has detected that the electrical voltage reaching the air brake solenoid circuit is below the expected operating threshold. This typically indicates an open circuit, a short to ground, high resistance in the wiring harness, or a failing solenoid coil.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R

1. 1

   Inspect the wiring harness and connectors between the CCU and the air brake solenoid for chafing, corrosion, or loose pins

2. 2

   Perform a voltage drop test at the air brake solenoid connector with the circuit activated. If voltage is low, probe backward toward the CCU to locate the exact point of the voltage drop

3. 3

   Perform a ground check by moving toward the load and ground terminal to locate any voltage drop on the ground side of the circuit

4. 4

   Unplug the air brake solenoid and measure the resistance across its coil pins with a multimeter to ensure the coil is not internally shorted or open (compare to OEM specifications)

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent accidental shorts during repair.

2. 2

   Repair Wiring

   If the diagnostic checks revealed high resistance, an open circuit, or a short to ground in the harness, repair the damaged section of wire or replace the faulty connector.

3. 3

   Replace Solenoid

   If the wiring and CCU output are verified as good but the solenoid coil failed the resistance test, replace the air brake solenoid valve. Relieve any residual air pressure in the brake system before removing the valve. Disconnect the air lines and the electrical connector. Unbolt the old solenoid and install the new one. Reconnect the air lines and electrical connector securely.

4. 4

   Test and Clear Codes

   Reconnect the battery, start the tractor, and allow the air system to build pressure. Perform an operational check of the air brakes and use a diagnostic tool to clear the 524191.04 fault code.