Case IH 520597-04 - BCM – BCM: High power voltage supply b - out of range - low

The voltage being supplied to the 'B' high-power circuit of the control module has dropped below the minimum acceptable operating threshold. This is typically caused by a failing battery, a blown fuse, a faulty relay, high resistance in the wiring harness (such as corrosion), or a poor ground connection.

• MAGNUM AFS Connect
• Magnum 180 AFS Connect
• Magnum 200 AFS Connect
• Magnum 220 AFS Connect
• Magnum 240 AFS Connect
• Magnum 250 AFS Connect
• Magnum 280 AFS Connect
• Magnum 310 AFS Connect
• Magnum 340 AFS Connect
• Magnum 380 AFS Connect
• Magnum 400 AFS Connect

1. 1

   Verify overall battery health and ensure the battery isolator relay is functioning correctly and passing full voltage

2. 2

   Locate the main power distribution box and test the specific fuses and relays that provide high power to the BCM

3. 3

   Disconnect the BCM connectors and inspect the pins for corrosion, moisture, or pushed-out terminals

4. 4

   Using a multimeter, measure the voltage at the BCM connector for the 'High power voltage supply b' pin while the system is under load. Compare this to the battery voltage to identify any voltage drop across the harness.

5. 5

   Check the main chassis grounds and the specific ground pins for the BCM to ensure they are clean and tight

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent accidental shorts during testing.

2. 2

   Access the BCM

   Locate the Body Control Module (typically located in the cab console or electrical distribution area).

3. 3

   Test the Supply Circuit

   Remove the fuse/relay responsible for BCM Power Supply B. Test the component for continuity. Replace if blown or faulty.

4. 4

   Inspect Wiring

   Trace the wiring harness from the fuse panel to the BCM. Look for chafing, pinched wires, or melted insulation.

5. 5

   Clean Connectors

   If the connectors show signs of oxidation, clean them thoroughly with a dedicated electrical contact cleaner and apply dielectric grease.

6. 6

   Repair High Resistance

   If the voltage drop test revealed low voltage at the connector but good voltage at the fuse, repair or replace the affected section of the wiring harness.

7. 7

   Module Replacement (If Necessary)

   If full battery voltage and solid grounds are verified at the BCM connector, but the module still logs the 520597-04 code, the BCM has an internal hardware failure and must be replaced.

8. 8

   Clear and Retest

   Reconnect the battery, clear the fault codes using an electronic service tool (EST), and cycle the key to verify the code does not return.