Case IH 518502-06 - BCM – BCM: Air Conditioner Clutch Solenoid Driver - Short circuit to ground

The control module has detected a short circuit to ground on the Air Conditioner Clutch Solenoid Driver circuit. The electrical current on the control wire supplying power to the A/C compressor clutch is bypassing the intended load and finding a direct path to the machine's chassis ground, causing the system to disable the A/C clutch driver to protect the circuit.

• MAGNUM AFS Connect
• Magnum 180
• Magnum 200
• Magnum 215
• Magnum 220
• Magnum 230
• Magnum 240
• Magnum 400
• Puma
• Steiger
• Patriot Sprayer

1. 1

   Inspect the wiring harness running from the BCM to the A/C compressor clutch for chafed insulation, pinched wires, or melted areas

2. 2

   Turn the key switch to the OFF position and disconnect the electrical connector at the A/C compressor clutch

3. 3

   With the clutch disconnected, use a multimeter to check for continuity between the A/C clutch supply wire (harness side) and a known good chassis ground to test for a harness short

4. 4

   Measure the resistance across the A/C compressor clutch coil pins; a reading near 0 ohms indicates the clutch coil is internally shorted to ground

5. 5

   Check the A/C clutch relay and associated fuses (often F29 or F30) to ensure a melted relay isn't causing a dead short in the power distribution box

1. 1

   Power Down

   Park the machine on level ground, turn off the engine, apply the parking brake, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Repair Wiring

   If the diagnostic tests revealed a short in the harness, locate the chafed section. Cut out the damaged wire, splice in a new section using weather-sealed heat-shrink butt connectors, and wrap the harness in protective loom.

3. 3

   Replace Clutch Coil

   If internally shorted, remove the drive belt from the A/C compressor, remove the center retaining nut on the compressor clutch hub, and use a puller to remove the clutch plate and pulley. Remove the snap ring holding the field coil in place, slide the old coil off, install the new clutch coil, replace the snap ring, and reinstall the pulley and clutch plate. Ensure the proper air gap is set according to the compressor specifications.

4. 4

   Reassembly

   Reconnect the A/C clutch electrical connector and reinstall the drive belt.

5. 5

   Clear Codes

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) to clear the 518502-06 fault code from the BCM.

6. 6

   Operational Test

   Start the tractor, turn on the A/C blower, and verify that the compressor clutch engages without tripping the fault code.