Case IH 518150-06 - BCM – BCM: Electrical crank power relay - short circuit to ground

The system has detected that the control circuit for the electrical crank power relay (starter relay) is shorted to ground. Voltage is finding an unintended path to the chassis ground before completing its normal circuit, which can prevent the machine from cranking or cause blown fuses.

• MAGNUM AFS Connect
• Magnum 400 AFS Connect
• Puma 200
• Puma 215
• Puma 230

1. 1

   Battery & Power Check: Ensure the battery is fully charged and the battery isolator switch is functioning correctly.

2. 2

   Relay Inspection: Locate the electrical crank power relay in the main power distribution box. Remove the relay and inspect the pins for melting, corrosion, or arc marks.

3. 3

   Harness & Ground Check: Inspect the wiring harness running from the BCM to the relay block. Look for chafed wire insulation rubbing against the tractor chassis (a common cause for a short to ground).

4. 4

   Circuit Testing: With the relay removed and the battery disconnected, use a multimeter to test the control wire from the BCM to the relay socket for continuity to ground. If there is continuity, the wire is shorted.

5. 5

   Relay Coil Test: Test the relay itself with a multimeter to see if the internal coil has collapsed/shorted out.

1. 1

   Disconnect Power

   Turn off the master battery disconnect switch and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Isolate the Fault

   Based on your diagnostic checks, determine if the fault is the relay itself or the wiring harness.

3. 3

   Replace the Relay (If faulty)

   If the relay coil is shorted, plug a new OEM starter/crank power relay into the distribution block.

4. 4

   Repair the Wiring (If shorted)

   If the harness is chafed and shorting to the chassis, carefully open the wire loom. Cut out the damaged section of the wire, splice in a new section of equivalent gauge wire, solder the connection, and seal it with marine-grade heat shrink. Re-loom and secure the harness away from sharp metal edges.

5. 5

   Reassemble and Test

   Reconnect the battery and turn on the master disconnect.

6. 6

   Clear Codes

   Connect a diagnostic tool to the BCM, clear the 518150-06 fault code, and attempt to crank the engine to verify the repair.