Case IH 518390-04 - DEC – Transmission Control Unit (TCU) or Vehicle Control Unit (VCU): Park brake primary valve solenoid electrical circuit fault voltage below normal.

The system has detected that the voltage in the circuit controlling the primary parking brake solenoid is below the expected normal range. This typically indicates a short to ground in the wiring harness or an internal short within the solenoid coil itself.

• MAGNUM AFS Connect
• Steiger AFS Connect

1. 1

   Visually inspect the wiring harness leading to the park brake control valve block for chafing, melted insulation, or pinch points that could cause a short to ground.

2. 2

   Disconnect the harness from the park brake solenoid and check the pins for corrosion, moisture, or damage.

3. 3

   Test the circuit with a multimeter to check the voltage supply at the connector with the key on, and check the ground circuit for continuity.

4. 4

   Measure the resistance across the pins of the solenoid coil itself. A reading near zero ohms indicates the coil is internally shorted and pulling the circuit voltage down.

1. 1

   Secure the Machine

   Park the tractor on a flat, level surface. Chock the wheels securely, as you will be disabling the parking brake system during the repair.

2. 2

   Relieve Pressure

   Ensure the machine is off and hydraulic pressure in the brake circuit is relieved.

3. 3

   Locate the Solenoid

   Find the primary park brake solenoid on the brake control valve assembly.

4. 4

   Disconnect Wiring

   Unplug the electrical connector from the faulty solenoid.

5. 5

   Remove the Coil

   Remove the retaining nut at the end of the solenoid valve stem. Slide the faulty solenoid coil off the valve cartridge. (Note: You usually do not need to remove the hydraulic valve cartridge itself, which prevents fluid loss).

6. 6

   Install the New Coil

   Slide the replacement solenoid coil onto the valve stem and secure it with the retaining nut. Do not overtighten.

7. 7

   Reconnect

   Plug the electrical harness back into the new solenoid.

8. 8

   Test

   Turn the key on, clear the fault codes via the AFS Pro display or diagnostic tool, and cycle the electronic park brake switch to ensure the code does not return and the brake engages/disengages properly.