Case IH 520603-05 - BCM – BCM: Work lamp #10 - open circuit

The Body Control Module (BCM) monitors the electrical current flowing to the tractor's exterior work lamps. When the operator turns on the work lights, the BCM expects to see a specific current draw. The FMI 05 (Failure Mode Identifier 05) indicates an "open circuit" or "current below normal." This means the electrical path to Work Lamp #10 is broken, the bulb is burnt out, the lamp is unplugged, or there is a severed wire in the harness preventing current from flowing.

• MAGNUM AFS Connect
• Magnum AFS Connect Series
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect
• Steiger AFS Connect
• Optum AFS Connect

1. 1

   Consult the operator's manual lighting diagram to identify exactly which physical light corresponds to Work Lamp #10 on your specific cab configuration.

2. 2

   Inspect the lamp for obvious physical damage, a shattered lens, or a burnt-out halogen filament.

3. 3

   Unplug the lamp and inspect the wiring connector for water intrusion, green corrosion, or pushed-out pins.

4. 4

   With the work lights commanded ON, use a multimeter to check for 12V at the power pin of the lamp's harness connector.

5. 5

   Check for continuity between the ground pin on the lamp's harness connector and a clean chassis ground.

6. 6

   If voltage and ground are present, temporarily swap the suspect lamp with a known-good lamp from another position to see if the fault follows the lamp or stays with the circuit.

1. 1

   Power Down

   Turn off the tractor, remove the key, and turn off the battery isolator switch to prevent accidental short circuits while working on the BCM harness.

2. 2

   Access the Lamp

   Safely access Work Lamp #10. Disconnect the pigtail connector.

3. 3

   Address the Component

   If the lamp is faulty: Replace the halogen bulb (do not touch the new glass with bare fingers) or replace the entire sealed LED housing. If the connector is corroded: Cut back the damaged wire and splice in a new OEM pigtail connector using weather-sealed heat-shrink butt connectors.

4. 4

   Harness Repair

   If the lamp and connector are good but you have no voltage, trace the wiring harness back toward the BCM. Look for pinch points, rodent damage, or chafing where the harness routes along the cab frame or fenders. Repair any broken wires.

5. 5

   Reassembly and Clearing

   Reconnect the lamp. Turn the battery isolator back on, start the tractor, and turn on the work lights.

6. 6

   Verify

   Check the AFS Pro display to ensure the 520603-05 code has moved from "Active" to "Inactive" or clear the code entirely using the display's diagnostic menu.