Case IH 2655-03 - BCM – BCM: Headlamp low beam right - short circuit to B+

A "short circuit to B+" (Battery Positive) or "unwanted power" condition means that an electrical path exists between the right low beam circuit and a power source when it is not intended to exist. The controller logic detects that the circuit is powered even when the headlamp switch is turned off. This is typically caused by chafed wiring touching a live wire, a melted connector, or an internal failure within the control module.

• MAGNUM AFS Connect
• Case IH Magnum (AFS Connect models)
• Case IH Puma (e.g., 200, 215, 230)

1. 1

   Inspect the right-hand headlamp assembly and its connector for signs of melting, water intrusion, or corrosion.

2. 2

   Disconnect the right headlamp. With the tractor key ON but the headlamp switch OFF, use a multimeter to measure voltage at the headlamp connector. If 12V is present, unwanted power is confirmed.

3. 3

   Disconnect the lighting harness from the BCM. Check for continuity between the right low beam power wire and other power circuits in the harness. If there is continuity, the short is in the wiring harness.

4. 4

   If the wiring harness tests perfectly fine (no shorts to power), the short circuit to B+ may be internal to the Body Control Module (e.g., a stuck internal relay or shorted driver).

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the tractor's battery to prevent electrical shock or further component damage.

2. 2

   Trace the Harness

   Follow the wiring harness from the right headlamp back toward the BCM. Pay close attention to pinch points, areas where the harness routes near hot engine components, or places where the loom rubs against the tractor frame.

3. 3

   Repair the Wiring

   If a chafed or melted wire is found, cut out the damaged section. Splice in a new section of wire using proper automotive-grade crimp connectors and weather-sealed heat shrink tubing.

4. 4

   Module Replacement (If Necessary)

   If the wiring harness is completely intact and the short is isolated to the BCM itself, the BCM must be replaced or sent to a specialized CNH electronics repair facility.

5. 5

   Reassembly and Testing

   Reconnect all harnesses and the battery. Use a diagnostic tool to clear the 2655-03 fault code. Turn on the tractor and cycle the headlamps to verify the right low beam operates correctly and the code does not return.