Case IH 520586-05 - BCM – BCM: Trailer left turn indicator - open circuit

The system has detected an open circuit in the wiring or component responsible for the trailer's left turn signal/indicator. This means the electrical path is broken, often due to a disconnected trailer plug, a severed wire, or a burnt-out bulb on the implement.

• MAGNUM AFS Connect
• Magnum 180 AFS Connect
• Magnum 200 AFS Connect
• Magnum 220 AFS Connect
• Magnum 240 AFS Connect
• Magnum 250 AFS Connect
• Magnum 280 AFS Connect
• Magnum 310 AFS Connect
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect

1. 1

   Check the Connection: Ensure the implement/trailer is actually plugged into the tractor's 7-pin socket. If the tractor is operated without a trailer or if the plug was pulled out during field operation, this open circuit code will trigger.

2. 2

   Inspect the 7-Pin Socket: Inspect the tractor's rear 7-pin trailer connector for corrosion, dirt, or physical damage.

3. 3

   Test the Left Turn Circuit: On a standard 7-pin agricultural connector, Pin 3 (Yellow wire) is designated for the Left Hand Flash and Turn Lights, and Pin 1 (White wire) is the Ground. Test Pin 3 for voltage when the left turn signal is activated.

4. 4

   Inspect Implement Wiring: Check the trailer/implement's left turn bulb to ensure it is not burnt out. Inspect the yellow wire on the implement side for breaks or pinches.

5. 5

   Harness Continuity: If the socket has no power, trace the wiring harness from the rear 7-pin connector back to the BCM to check for severed wires or loose harness connectors.

1. 1

   Clear the Code / Reconnect

   If the implement was simply unplugged, plug the 7-pin connector back into the tractor socket and clear the fault codes.

2. 2

   Repair the Socket/Wiring

   If Pin 3 (Left Turn) or Pin 1 (Ground) in the 7-pin socket is heavily corroded or damaged, cut back the damaged wire and splice in a new 7-pin socket receptacle.

3. 3

   Replace the Bulb

   If the open circuit is on the implement side, replace the blown left turn indicator bulb or the damaged LED assembly on the trailer.

4. 4

   BCM Replacement (Worst Case)

   If the wiring harness has perfect continuity from the BCM to the rear socket, the ground is good, and there is no output from the BCM, the Body Control Module itself may have an internal fault and require replacement and reprogramming by a dealer.