Case IH 520580-03 - BCM – BCM: Short circuit to B+ on the front right turn light circuit

The control module is detecting continuous battery voltage on the turn signal circuit even when the signal is not commanded on, or the circuit is shorted directly to a 12V power source, preventing normal operation.

• MAGNUM AFS Connect
• Steiger AFS Connect

1. 1

   Use the battery isolator switch to disconnect battery power to prevent accidental shorts

2. 2

   Inspect the front right turn light housing for physical damage, cracked lenses, or water ingress

3. 3

   Trace the wiring harness from the front right turn light back to the BCM, looking for pinched wires, chafing, or melted insulation

4. 4

   Disconnect the front right turn light connector, reconnect the battery, and use a multimeter to check for voltage at the signal pin with the turn signal switch off

5. 5

   Check the fuses and relay box in the rear cab compartment for stuck closed relays or incorrect fuses

1. 1

   Isolate the Circuit

   Turn off the machine and engage the battery isolator to cut power to the BCM and fuse modules.

2. 2

   Disconnect the Component

   Unplug the front right turn light assembly.

3. 3

   Isolate the Short

   If the wiring harness was found to be chafed and touching a power wire, cut out the damaged section. Solder in a new section of wire and seal it with marine-grade heat shrink tubing. If the harness tests fine but the light assembly is internally shorted, the assembly must be replaced. Do not attempt to open and repair sealed LED/halogen housings.

4. 4

   Reassemble and Test

   Plug the connector back into the light assembly. Disengage the battery isolator to restore power.

5. 5

   Verify Operation

   Turn the ignition on and activate the right turn signal. Verify that the light flashes correctly and that the dashboard indicator functions.

6. 6

   Clear Codes

   Connect the Case IH diagnostic tool to the service port and clear the inactive 520580-03 fault code from the BCM memory.