Case IH 518109-03 - BCM – BCM: Work lamp #12 - short circuit to B+

The control module has detected that the electrical circuit supplying power to Work Lamp #12 is shorted to battery voltage (B+). This occurs when the circuit receives 12V power unexpectedly, usually due to a wiring harness failure (wires melting or rubbing together) or an internal short within the lamp assembly itself.

• MAGNUM AFS Connect
• Case IH Magnum AFS Connect series (250, 280, 310, 340, 380, 400)
• Case IH Steiger AFS Connect series

1. 1

   Consult the operator's manual to locate the specific physical position of Work Lamp #12 on the cab roof, pillar, or hood.

2. 2

   Disconnect the electrical connector at Work Lamp #12. Turn the ignition on and check if the fault code changes from short to B+ to an open circuit code. If it does, the short is internal to the LED work lamp assembly.

3. 3

   If the code remains active as a short to B+ with the lamp disconnected, the short is in the wiring harness. Inspect the harness routing from the BCM to the lamp for pinch points, chafing, or melted insulation where the lamp's power wire might be touching a constant 12V source.

4. 4

   Inspect the BCM output pins and the work lamp connector for water ingress, corrosion, or bent pins that could bridge the power circuits.

5. 5

   With the work lamp commanded off via the AFS Pro 1200 display, use a multimeter to probe the power pin at the lamp connector. If it reads 12V, the harness is shorted to power.

1. 1

   Power Down

   Turn off the tractor and engage the manual battery isolator switch to disconnect power to the BCM.

2. 2

   Access the Fault

   Gain access to Work Lamp #12 and its wiring pigtail.

3. 3

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a harness short, carefully open the wire loom at the damaged section. Splice and repair the damaged wires using OEM-approved environmental splices and heat-shrink tubing. Re-loom and secure the harness away from pinch points.

4. 4

   Replace Lamp (If Applicable)

   If the lamp is internally shorted, remove the mounting hardware, detach the lamp bracket, and install a new LED work lamp assembly.

5. 5

   Reassemble and Clear Codes

   Reconnect the work lamp, turn the battery isolator switch back on, and power up the tractor. Use the AFS Pro 1200 monitor or the Case IH Electronic Service Tool (EST) to clear the inactive BCM fault codes.

6. 6

   Verify Operation

   Turn on the work light circuit to ensure the lamp illuminates correctly and the fault code does not return.