Case IH 2851 – Transmission Controller (Trans / TCU): The Park Brake Driver has detected an over current or an open circuit condition

The control module is monitoring the electrical circuit that commands the park brake solenoid. It has detected either a break in the wiring/coil (open circuit) or a short circuit causing an excessive electrical draw (over current).

• Magnum
• Steiger T4B
• Case IH Magnum Series: 235 - 340 (Series 4)
• Case IH STX Steiger Series: 350 to 600 horsepower models

1. 1

   Check for Related Codes: Look for accompanying codes, such as 2852 (The Park Brake is stuck on by no electrical power supplied to the solenoid when driver is commanded on).

2. 2

   Visual Inspection: Inspect the wiring harness running from the Transmission Controller to the park brake solenoid on the transmission valve block. Look for rubbed, pinched, or broken wires.

3. 3

   Connector Check: Disconnect the park brake solenoid connector. Check for water intrusion, corrosion, or pushed-back pins.

4. 4

   Coil Resistance Test: Using a multimeter, measure the resistance across the pins of the park brake solenoid coil. An infinite reading indicates an internal open circuit, while a reading of near-zero ohms indicates a dead short (which causes the over-current condition).

1. 1

   Secure the Machine

   Park the tractor on a flat, level surface. Turn off the engine and chock the wheels securely. Because you are working on the park brake circuit, the machine could roll if the brake disengages or loses pressure.

2. 2

   Locate the Solenoid

   Locate the park brake solenoid valve on the transmission hydraulic control block.

3. 3

   Address Wiring Issues

   If the diagnostic checks revealed a damaged harness or corroded connector, splice in a new connector pigtail or repair the broken wire using weather-sealed heat shrink connectors.

4. 4

   Replace the Solenoid (if faulty)

   If the solenoid coil failed the resistance test, remove the retaining nut holding the coil to the valve stem. Slide the old coil off and install the new replacement coil. (If the entire cartridge valve is damaged, unthread the valve from the block and install a new one, taking care to replace the O-rings).

5. 5

   Reconnect and Clear

   Reconnect the electrical harness to the solenoid.

6. 6

   Test

   Turn the key on, use the tractor's diagnostic display to clear the fault codes, and cycle the park brake switch. Verify that code 2851 does not return and that the park brake engages and disengages properly.