Case IH 520600-06 - BCM – BCM: Work lamp #1 - short circuit to ground

The power supply circuit for Work Lamp #1 has an unintended, direct path to ground (the machine's chassis or a ground wire) before the electrical load (the lamp itself). When the circuit is energized, this creates a path of least resistance, causing an excessive current draw. The control module detects this voltage drop/current spike and logs the fault, typically disabling the circuit to prevent wiring damage or fire.

• MAGNUM AFS Connect
• Magnum Series (180, 200, 220, 240, 250, 280, 310, 340, 380)
• Puma Series (165, 180, 195, 210, 225)
• Farmall Series (55A, 95U, 105U, 115U, 100C)
• Axial-Flow Combines

1. 1

   Inspect Work Lamp #1 and its pigtail connector for melted plastic, water intrusion, or an internally shorted bulb/LED board.

2. 2

   Check the cab fuse box for blown work lamp fuses (typically 15A or 20A) and inspect the work lamp relay for an internal short to ground.

3. 3

   Perform a continuity to ground test by disconnecting the connector at Work Lamp #1 and the BCM, then measuring continuity between the power supply wire and chassis ground.

4. 4

   Inspect the wiring harness for chafing, rubbing, or pinching, particularly along the cab frame, fenders, or hinges.

1. 1

   Isolate the Power

   Turn off the ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Isolate the Short

   If the continuity test confirmed a short in the harness, trace the wire from the BCM to the work lamp. Pay close attention to areas where the harness passes through metal bulkheads or bends around the cab frame.

3. 3

   Repair the Wiring

   Once the chafed or pinched wire is located, cut out the damaged section. Splice in a new section of wire using marine-grade, heat-shrink butt connectors to ensure a weather-tight seal.

4. 4

   Component Replacement (If Applicable)

   If the wiring is intact but the work lamp relay or the lamp assembly itself tested as internally shorted, replace the faulty component.

5. 5

   Reassembly and Testing

   Reconnect the BCM and the work lamp. Reconnect the battery. Replace any blown fuses. Turn the ignition ON and activate the work lamps to verify the fault is cleared and the lamp operates correctly.