Case IH 520442-06 - BCM – BCM: Roof mounted headlamp high beam left - short circuit to ground

The system has detected that the electrical circuit supplying power to the left roof-mounted high beam headlamp is making unintended contact with a ground source. This causes the normal resistance to drop, pulling excess current and disabling the light to protect the circuit.

• MAGNUM AFS Connect
• Magnum 180 AFS Connect
• Magnum 200 AFS Connect
• Magnum 220 AFS Connect
• Magnum 240 AFS Connect
• Magnum 250 AFS Connect
• Magnum 280 AFS Connect
• Magnum 310 AFS Connect
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect

1. 1

   Consult the vehicle's electrical schematic to logically trace the wiring path from the BCM to the left roof headlamp

2. 2

   Inspect the left roof headlamp housing and harness for water intrusion or physical damage caused by heavy vehicle vibration

3. 3

   Disconnect the headlamp and use a Digital Multimeter (DMM) to test for continuity between the power wire and the chassis ground

4. 4

   Isolate the component from the wiring: if the wiring harness does not show a short to ground when disconnected, the short is likely internal to the headlamp assembly

5. 5

   Use the CNH EST (Electronic Service Tool) to read the live status of the fault and verify if the code is active or stored

1. 1

   Power Down

   Turn off the tractor. Disconnect the battery ground cable to ensure the electrical system is safe to work on.

2. 2

   Access the Headlamp

   Safely access the cab roof and remove the left high beam headlamp assembly.

3. 3

   Inspect the Harness

   Trace the wiring harness from the roof headlamp down toward the BCM. Look for pinched wires, chafed insulation rubbing against the cab frame, or melted connectors.

4. 4

   Repair the Short

   If the wiring is chafed and grounding out against the chassis, cut out the damaged section of the wire and splice in a new wire using weather-sealed heat shrink connectors. If the short is internal to the headlamp assembly (the wiring harness tests fine), replace the headlamp unit.

5. 5

   Reassembly

   Reconnect the headlamp and secure the wiring harness, ensuring it is routed away from sharp metal edges.

6. 6

   Clear Codes

   Reconnect the battery. Use the CNH EST diagnostic tool (or the AFS Pro 1200 display) to clear the 520442-06 fault code and test the high beams to ensure the BCM is regulating voltage properly.