Case IH 520445-06 - BCM – BCM (Body Control Module) or LCM (Lighting Control Module): Roof mounted headlamp low beam left - short circuit to ground

The control module has detected that the supply voltage line to the left roof-mounted low beam headlamp is shorting directly to the vehicle's chassis ground, or the lamp itself has an internal short.

• MAGNUM AFS Connect
• Puma
• Magnum
• Steiger
• Axial-Flow

1. 1

   Inspect the left roof-mounted headlamp bulb and its internal housing for melting, internal shorts, or water ingress

2. 2

   Inspect the wiring harness running from the BCM to the roof headlamp for pinched wires, chafing against the cab frame, or melted insulation

3. 3

   Disconnect the headlamp and inspect the connector pins for corrosion or bridging to the ground pin

4. 4

   With the lamp disconnected, use a multimeter to measure the resistance between the power supply wire and the chassis ground (a reading of zero or very low ohms confirms a short in the wiring)

1. 1

   Isolate the circuit

   Turn off the machine's key switch and disconnect the battery to prevent further damage to the BCM.

2. 2

   Remove the headlamp

   Unbolt the left roof-mounted headlamp assembly and disconnect the wiring pigtail.

3. 3

   Test the output

   Reconnect the battery and turn the light switch to the low beam position. Test the voltage at the connector. If the fuse blows or the BCM cuts power immediately, the short is in the harness.

4. 4

   Repair the harness

   Trace the wire back down the cab pillar to the BCM. Locate the chafed or pinched section of the wire. Cut out the damaged section, splice in a new wire using weather-sealed heat-shrink butt connectors, and wrap it in protective loom.

5. 5

   Replace the bulb or assembly

   If the harness tests fine (infinite resistance to ground when disconnected), the short is internal to the headlamp assembly. Replace the bulb or the entire sealed headlamp unit.

6. 6

   Clear codes

   Reconnect all components, turn the key on, and verify the headlamp operates correctly. Clear the inactive 520445-06 code from the BCM using the diagnostic menu or a service tool.