Case IH 17656 (F-518399-04) - ECU – Engine Control Module (ECM): ECM 12/24 volt actuator supply 4 is shorted to ground

The ECM provides a 12V or 24V power supply to specific engine actuators via a dedicated circuit known as "Supply 4". The system has detected that this specific supply circuit is shorted directly to ground, which will prevent the actuators on this circuit from functioning. The specific ECM pins for Actuator Supply 4 are 5.11 and 6.34.

• VESTRUM CVX
• Magnum (CVT/CVX)
• Maxxum CVX
• Optum CVX
• Puma (CVX/X/EP)
• Steiger
• Quadtrac
• Vestrum
• Axial-Flow 5150
• Axial-Flow 6150
• Axial-Flow 7150
• Axial-Flow 7250
• Axial-Flow 8250
• Axial-Flow 9250
• Patriot 3250
• Patriot 4450
• Farmlift 737
• Farmlift 742
• Case Graders
• Case Wheel Loaders

1. 1

   Verify the Code: Ensure the code is active. If multiple actuator supply codes are present, diagnose them in order of appearance.

2. 2

   Inspect the ECM Connectors: Locate the Bosch MD1CE101 ECM on the engine. Disconnect the harness and inspect the ECM pins and harness terminals for water ingress, corrosion, or bent pins, specifically focusing on pins 5.11 and 6.34.

3. 3

   Harness Continuity and Short Test: Using a multimeter, test the wiring harness at pins 5.11 and 6.34 for continuity to ground. A reading of low resistance to ground confirms the short.

4. 4

   Isolate the Short: Disconnect the actuators powered by Supply 4 one at a time. If the short to ground disappears on your multimeter when a specific actuator is unplugged, that actuator is internally shorted. If the short remains with all actuators unplugged, the wiring harness itself is chafed or pinched against the machine's chassis or engine block.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical arcing or further module damage.

2. 2

   Locate the Short

   Based on the isolation test above, trace the wiring harness from ECM pins 5.11 and 6.34 to the respective actuators. Look for areas where the harness routes tightly around metal brackets or engine components where rubbing may have occurred.

3. 3

   Repair the Wiring

   If a chafed wire is found, cut out the damaged section, splice in a new section of wire using weather-resistant heat-shrink butt connectors, and re-loom the harness. Ensure it is secured away from sharp edges.

4. 4

   Replace Faulty Components

   If the wiring is intact but an actuator was found to be internally shorted to ground, replace the faulty actuator.

5. 5

   Reassemble and Clear Codes

   Reconnect all actuators and the ECM harness. Reconnect the battery. Use the CNH Electronic Service Tool (EST) to clear the fault codes and run the engine to verify the repair.