Case IH 520567-03 - BCM – BCM: Electrical ignition power relay - short circuit to B+

The control circuit for the electrical ignition power relay has a short to battery positive (B+). The system is detecting voltage on the relay's control line when it should not be present, which can cause the relay to remain energized constantly, fail to switch properly, or cause erratic cab electrical behavior.

• MAGNUM AFS Connect
• Magnum 400 AFS Connect
• Steiger AFS Connect

1. 1

   Check for related code 520567-00 (Electrical ignition power relay - too many loads or faulty load), which can accompany this issue.

2. 2

   Locate the ignition power relay in the cab fuse/relay panel and inspect the relay and its socket for signs of melting, corrosion, or heat damage.

3. 3

   Swap the ignition relay with a known good relay of the same amperage to see if the fault clears (an internally fused relay can cause short-to-B+ symptoms).

4. 4

   Inspect the 'clean' ground going directly to the battery, the cab power relay ground connections, and the power stud where it comes through the cab floor.

5. 5

   Using a multimeter, test the wiring harness between the BCM and the ignition relay socket for continuity to a power source (short to B+).

1. 1

   Safe Shutdown

   Turn the ignition key to the OFF position. Wait 2 to 5 minutes before disconnecting the batteries. This wait time is critical on AFS Connect machines to allow the DEF/AdBlue system to purge and the ECUs to power down properly.

2. 2

   Disconnect Power

   Disconnect the negative battery cable to prevent accidental shorts during testing.

3. 3

   Access the Fuse/Relay Panel

   Open the cab fuse panel and locate the specific Ignition Power Relay triggering the fault (often designated as K-010, K-201, or similar depending on the exact trim).

4. 4

   Test/Replace the Relay

   Remove the relay. Test it with a multimeter. If the relay is stuck closed or fails resistance checks, replace it with a new OEM relay.

5. 5

   Repair Wiring (If Applicable)

   If the relay is good, trace the control wire from the relay block back to the BCM. Locate the area where the wire's insulation has rubbed through and is touching a 12V power source. Splice and repair the damaged wire using heat-shrink connectors.

6. 6

   Clean Grounds

   Remove the cab ground cables, clean the ring terminals and the mounting surface with a wire brush, and reattach them securely.

7. 7

   Reassembly

   Reinstall the relay, reconnect the battery, and turn the key ON. Use the diagnostic tool or AFS Pro monitor to clear the inactive fault codes. Cycle the key to ensure the code does not return.