Case IH 3481 – Engine Control Module (ECM): Coolant Pump digital actuator: Short Circuit to Battery error on the output power stage.

The engine control system has detected an electrical short to an external voltage source (battery positive) on the control circuit for the engine coolant pump's digital actuator. This condition prevents the module from properly regulating the coolant pump speed, which can lead to cooling system malfunctions.

• Magnum
• Steiger
• Puma
• Optum

1. 1

   Inspect the wiring harness running from the ECM to the Coolant Pump digital actuator for chafed wires, melted insulation, or pinched harnesses that could cause the control wire to touch a constant 12V/24V power source.

2. 2

   Perform a harness voltage test: Disconnect the connector at the Coolant Pump actuator, turn the key to the ON position (engine OFF), and use a multimeter to probe the control circuit pin on the harness side. Reading battery voltage indicates the harness is shorted to battery power.

3. 3

   If the wiring harness tests good (no voltage bleed-over), suspect an internal short within the Coolant Pump digital actuator's circuitry.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Isolate the Fault

   Based on the diagnostic checks, determine if the fault is in the harness or the actuator.

3. 3

   Repair the Harness (If Applicable)

   If a short to battery was found in the wiring, locate the damaged section. Splice and heat-shrink the damaged wires, or replace that section of the engine harness.

4. 4

   Replace the Actuator (If Applicable)

   If the harness is intact, the Coolant Pump digital actuator is defective. Drain the engine coolant below the level of the water pump. Disconnect the electrical connector and remove the mounting bolts for the coolant pump actuator (or the entire coolant pump assembly). Install the new actuator/pump and torque bolts to OEM specifications.

5. 5

   Reassemble and Refill

   Reconnect the electrical connector, refill the cooling system with the specified OAT coolant, and bleed the system of air.

6. 6

   Clear Codes

   Reconnect the battery, use a diagnostic service tool (like the CNH EST) to clear the inactive 3481 fault code, and run the engine to verify the pump operates without throwing a code.