Case IH 520591-00 - BCM – BCM: Backup alarm - too many loads or faulty load

This code indicates that the current draw on the backup alarm circuit is above normal. The system detects "too many loads" (excessive amperage draw), which is typically caused by a short circuit to ground, a short to power in the wiring harness, or an internal short/failure within the backup alarm unit itself.

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

1. 1

   Visually inspect the backup alarm (usually mounted at the rear) and wiring harness for chafed wires, melted insulation, or pinched lines shorting to the chassis.

2. 2

   Perform a disconnect test: Turn off the machine, disconnect the electrical connector at the backup alarm, and turn the key back on. If the code changes to 520591-05 (open circuit), the alarm is internally shorted and faulty.

3. 3

   If the code remains 520591-00 with the alarm unplugged, the short is in the wiring harness. Use a multimeter to test the power wire for a short to ground between the BCM and the alarm connector.

4. 4

   Inspect the BCM connectors and the alarm pigtail for water intrusion, mud, or corrosion, which can bridge pins and cause false load readings.

1. 1

   Power down machine

   Power down the machine and turn the battery disconnect switch to the OFF position.

2. 2

   Locate alarm

   Locate the backup alarm assembly at the rear of the machine.

3. 3

   Disconnect harness

   Depress the locking tab and disconnect the electrical harness connector from the alarm.

4. 4

   Remove alarm

   Remove the mounting bolts/nuts securing the alarm to its bracket.

5. 5

   Install new alarm

   Install the replacement backup alarm and tighten the mounting hardware.

6. 6

   Apply dielectric grease and connect

   Apply a small amount of dielectric grease to the electrical connector to prevent moisture ingress, then plug it into the new alarm.

7. 7

   Turn on battery

   Turn the battery disconnect switch back ON.

8. 8

   Verify operation

   Turn the ignition on, safely engage the reverse shuttle (with parking brakes applied), and verify the alarm sounds.

9. 9

   Clear fault code

   Clear the inactive 520591-00 fault code from the AFS display.