Case IH 12068 – Electronic Park Lock (EPL) controller or Central Control Unit (RE module): Trailer relay – output short circuit to ground

The control module has detected a short circuit to ground on the output line that supplies voltage to the trailer brake relay.

• Puma/Mid Range Magnum
• MAXXUM T4E
• Puma Series 150, 165, 180, 195, 210, 225 CVX
• Maxxum Series 125, 150
• Optum Series 270, 300 CVT
• Farmall Series 95U, 105U, 115U Pro EP
• Magnum Series
• Steiger Series

1. 1

   Check the hydraulic trailer brake relay (K-010 or K-011) for internal shorts.

2. 2

   Inspect the wiring harness from the trailer brake relay socket back to the EPL controller/Central Control Unit for chafed insulation, pinched wires, or exposed copper that is grounding out against the tractor chassis.

3. 3

   Inspect the fuse associated with the trailer brake relay circuit (often a 5A mini fuse, designated as F-036 on some models) to see if the short has caused it to blow.

4. 4

   Access the Electronic Park Lock sub-system via the diagnostic display and check 'Channel 2 - Electronic Park Lock Trailer Brake Relay Present' to ensure the module is correctly configured.

1. 1

   Power Down

   Turn off the tractor, remove the key, and engage the park brake. Ensure all pressure is relieved from hydraulic circuits.

2. 2

   Access the Relay Panel

   Open the main electrical distribution panel (MDP) to access the fuses and relays.

3. 3

   Test/Replace the Relay

   Remove the trailer brake relay (K-010/K-011). Use a multimeter to check for continuity to ground on the control circuit. If the relay is internally shorted, replace it.

4. 4

   Repair Wiring

   If the relay is good, use a multimeter to test the output wire from the EPL controller to the relay socket. If continuity to ground is found, physically trace the harness, locate the short, and repair the damaged wire using proper soldering and heat-shrink tubing.

5. 5

   Replace Blown Fuses

   If the short circuit caused the circuit protection to trip, replace the 5A mini fuse.

6. 6

   Clear Codes and Test

   Reconnect all components, turn the ignition on, and use the diagnostic interface to clear fault code 12068. Test the trailer brake function to ensure the code does not return.