Case IH 520587-06 - BCM – Body Control Module (BCM): Current above normal or grounded circuit (Short circuit to ground on the trailer's right turn indicator circuit)

The system has detected a short circuit to ground on the trailer's right turn indicator circuit. Voltage intended for the right turn signal bulb is finding a direct path to the chassis ground before passing through the load, causing an overcurrent situation that the controller shuts down to protect the circuit.

• MAGNUM AFS Connect
• Maxxum
• Puma
• Magnum
• Optum
• Steiger

1. 1

   Isolate the fault by disconnecting the trailer from the tractor's 7-pin socket, turning the key ON, clearing inactive DTCs, and activating the right turn signal to see if the code returns (if it returns, the short is on the tractor; if not, it is on the trailer)

2. 2

   Inspect the tractor's 7-pin socket for heavy corrosion, water intrusion, or debris bridging the pins

3. 3

   Test the trailer wiring using a multimeter set to ohms/continuity between Pin 5 (Green wire) and Pin 1 (White wire/ground) to check for a dead short

4. 4

   Inspect the trailer's right turn indicator bulbs for broken filaments that may have fallen across each other or shorted to the grounded base

1. 1

   Check for Crushed Wires

   If the fault is on the tractor side, remove the 7-pin socket from its mounting bracket. Repair any bare wires crushed between the socket housing and the tractor frame with heat-shrink tubing.

2. 2

   Replace the Socket

   If the tractor's 7-pin socket is heavily corroded or internally shorted, cut the wires back to clean copper and wire in a new OEM replacement socket.

3. 3

   Repair Trailer Harness

   If the fault is on the trailer, trace the green wire from the plug to the right tail light. Look for areas where the wire passes through the steel frame or fenders without a rubber grommet, and splice in new wire where damaged.

4. 4

   Clean Grounds

   Ensure the trailer's main ground wire (white) is securely bolted to bare metal on the tongue, and that the right tail light housing is properly grounded to a clean surface.

5. 5

   Test the System

   Reconnect the trailer, turn the ignition ON, and test the right turn signal to verify the lights flash correctly and the BCM does not log the 520587-06 code.