Case IH 520582-03 - BCM – BCM: Front and rear marker light right side - short circuit to B+

The control module has detected that the electrical circuit supplying the right-side front and rear marker lights is shorted to battery positive (B+). This indicates that the circuit is receiving voltage when it shouldn't be, usually due to a wiring harness failure where the marker light wire is rubbing against a constant power wire, or an internal short within the light assembly itself.

• MAGNUM AFS Connect
• Steiger AFS Connect

1. 1

   Visually inspect the right-side front and rear marker light assemblies for physical damage, water ingress, or melted housings that could cause an internal short.

2. 2

   Trace the wiring harness for the right-side marker lights back to the BCM. Look for pinch points, chafing against the frame, or melted insulation where the wire might be bridging with a 12V power source.

3. 3

   Disconnect the right-side marker lights. With the light switch turned OFF, use a multimeter to probe the signal wire at the connector. If 12V is present, the short to B+ is located within the wiring harness.

4. 4

   Inspect the BCM connectors for corrosion, bent pins, or moisture, which can bridge power pins to the lighting circuit pins.

1. 1

   Isolate Power

   Turn off the machine and disconnect the battery using the battery isolator switch to prevent electrical arcing during the repair.

2. 2

   Isolate the Short

   Disconnect the right front and right rear marker light assemblies from the main harness.

3. 3

   Test the Harness

   Reconnect the battery and test the harness-side connectors. If the short to B+ disappears when the lights are unplugged, the fault is an internal short inside one of the marker light assemblies. If the short to B+ persists on the multimeter, the fault is in the wiring harness.

4. 4

   Repair the Harness (If Applicable)

   If the harness is shorted, trace the wire back to the BCM. Locate the section where the wire insulation has rubbed through and is touching a live wire. Cut out the damaged section, splice in a new wire using weather-sealed heat shrink connectors, and re-loom the harness.

5. 5

   Replace the Component (If Applicable)

   If the light assembly is internally shorted, replace the affected right-side marker light assembly.

6. 6

   Clear and Verify

   Reconnect all components. Turn on the machine, clear the inactive 520582-03 fault code from the AFS Pro display, and toggle the marker lights to verify proper operation without tripping the code again.