Case IH 520579-05 - BCM – BCM: Rear Left Turn Light Open Circuit

The fault indicates an 'open circuit' or 'current below normal' in the rear left turn light circuit, preventing current from flowing to the left rear turn lamp.

• MAGNUM AFS Connect
• Magnum series
• Steiger series
• Farmall series

1. 1

   Visually inspect the wire harness, connectors, and the central electrical box/fuse panel for obvious damage, disconnected plugs, or a blown fuse.

2. 2

   Inspect the left rear turn lamp assembly to see if the halogen bulb is burnt out or if the LED matrix has failed.

3. 3

   Measure resistance between the BCM connector and the turn light connector to confirm harness continuity (should be less than 5 ohms). Gently shake the harness up and down while measuring to check for intermittent breaks.

4. 4

   Test the universal/combination switch by placing it in the 'left turn' position and measuring resistance across its terminals (a reading of less than 1 ohm is normal; higher indicates an internal open circuit).

1. 1

   Disconnect Power

   Turn the ignition switch to the OFF position and disconnect the battery ground before repairing electrical circuits to prevent module damage.

2. 2

   Replace Fuses

   If the diagnostic check revealed a blown fuse link in the central electrical box, replace it immediately with a spare of the exact same amperage (e.g., 20 amp).

3. 3

   Repair the Harness

   If the continuity test failed, locate the break in the wiring harness. Splice and solder the broken wire, then seal it with heat-shrink tubing to protect it from the elements.

4. 4

   Replace the Switch

   If the combination switch failed the resistance test, remove the steering column shroud, disconnect the switch harness, and install a new universal turn switch.

5. 5

   Replace the Light Assembly

   If the wiring and switch are good, but the light does not illuminate (or the bulb is blown), remove the mounting hardware for the rear left turn light and plug in a new assembly.

6. 6

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use the vehicle information display or a diagnostic tool to clear the previously active BCM codes. Test the left turn signal to ensure the code does not return.