Case IH 4012-03 - BCM – BCM: BCM right high beam short circuit

The right high beam headlamp circuit is shorted to a higher-than-normal voltage source (battery positive). This typically indicates that the wiring between the control module and the right headlamp is rubbing or melted against a live power wire, or there is an internal fault in a relay or switch supplying constant voltage when it shouldn't.

• MAGNUM AFS Connect
• MAXXUM series (100, 110, 115, 120, 125, 130, 140)
• PUMA series (115 through 230)
• MXM series (MXM120, MXM130, MXM140, MXM155, MXM175, MXM190)
• MX series
• Legacy series (51, 55, 95)
• AFX8010
• 2377
• 2388
• 2577
• 2588
• 7010
• 7120
• 8010
• 8120
• 9120

1. 1

   Use a dealer-level diagnostic tool to read the BCM input/output signals. Perform an Active Test to see if the signals used to activate the right high beam are being forcibly supplied from the BCM.

2. 2

   Check if the headlight switch or hazard light switch stays lit abnormally when the machine is off, which can indicate a hardware line issue preventing the system from going to sleep.

3. 3

   Inspect the main lighting harness and the specific Right Hand Headlamp connector (e.g., connector C059) for melted wires or exposed copper touching a power source.

4. 4

   Inspect the high beam relay and the high beam fuse for signs of melting or blown filaments.

1. 1

   Disconnect battery

   Disconnect the machine's battery to prevent further electrical damage.

2. 2

   Trace wiring harness

   Trace the right high beam wiring harness from the BCM to the right headlamp assembly, looking for the point where the circuit is shorted to a voltage source (B+).

3. 3

   Repair harness

   Repair or replace the damaged section of the lighting harness.

4. 4

   Replace damaged components

   If the short circuit damaged the relay or the bulb, replace the high beam relay and/or the right headlamp bulb.

5. 5

   Check and replace fuse

   Check the high beam fuse (typically a 15A Mini Blue fuse) and replace it if it has blown.

6. 6

   Clear DTCs

   Reconnect the battery and use a diagnostic scan tool to clear the DTCs from the BCM.

7. 7

   Test system

   Test the high beam function to ensure the short has been resolved.