Case IH 520575-05 - BCM – Body Control Module (BCM): Turn light front left - open circuit

The fault code indicates an "open circuit" condition in the front left turn signal circuit. This means the Body Control Module (BCM) is sending voltage to the front left turn light but is not detecting the expected electrical current draw returning through the ground. This lack of continuity is most commonly caused by a blown bulb, a severed wire, an unplugged connector, or a heavily corroded ground connection.

• MAGNUM AFS Connect
• Case IH AFS Connect Magnum Tractors (Models 180, 200, 220, 240, 250, 280, 310, 340, 380)
• Case IH Puma series tractors
• Case IH Maxxum series tractors
• Case IH Steiger series tractors
• Case IH Farmall
• Case IH Pro series 85, 100, 110, 115, 125

1. 1

   Inspect the front left turn signal housing and bulb for a broken filament or blackened glass (blown bulb cause)

2. 2

   Check the wiring harness connector at the front left turn light to ensure it is fully seated, locked, and free of green corrosion, moisture, or pushed-back terminals (connector/corrosion cause)

3. 3

   Perform a voltage test by probing the positive pin on the harness side with the ignition ON and left turn signal activated; you should see a pulsing 12V signal (wiring/power cause)

4. 4

   Perform a ground continuity test by probing the ground pin on the harness side to a clean chassis ground; resistance should be near 0 ohms (bad ground cause)

5. 5

   Bypass components to isolate the fault: if 12V and ground are good, the fault is internal to the light assembly; if lacking voltage or ground, the fault is in the wiring harness

1. 1

   Power Down

   Turn off the tractor ignition, remove the key, and turn off the battery disconnect switch to prevent accidental short circuits.

2. 2

   Access the Light

   Depending on the model, remove the front grille, hood panel, or cab corner trim required to access the rear of the front left turn light assembly.

3. 3

   Disconnect Harness

   Depress the locking tab on the electrical connector and pull it free from the light assembly.

4. 4

   Replace the Component

   If the bulb is blown: Twist the bulb socket counterclockwise to remove it from the housing. Replace the bulb (commonly a P21W) and reinstall. If the LED assembly is failed: Unbolt the mounting hardware securing the light housing to the tractor. Install the new OEM light assembly and tighten the bolts. If the wiring is damaged: Locate the break or chafed wire. Cut out the damaged section, strip the ends, and splice in a new section of wire using weather-sealed (heat-shrink) butt connectors.

5. 5

   Clean and Protect

   Spray the electrical connector pins with contact cleaner and apply a small amount of dielectric grease to prevent future moisture intrusion.

6. 6

   Reassemble and Test

   Reconnect the wiring harness. Turn on the battery disconnect and ignition. Activate the left turn signal to verify the light flashes and the BCM clears the 520575-05 fault code from the dash display.