Case IH 19520 – Diesel Engine Control Unit (ECU): Low Temperature Coolant Pump actuator: Open Load error on the output power stage

The Engine Control Unit (ECU) is attempting to send power to the actuator, but the electrical circuit is incomplete (open). The underlying condition is specifically defined as broken wiring, disconnected wiring, or an internally defective Low Temperature Coolant Pump actuator.

• Tier 4b
• Case IH machines with FPT diesel engines utilizing a secondary low-temperature coolant circuit

1. 1

   Check the electrical connector at the Low Temperature Coolant Pump actuator to ensure it is not unplugged, loose, or heavily corroded.

2. 2

   Trace the wiring harness from the coolant pump actuator back to the ECU. Look for broken, chafed, or disconnected wires that would cause an open circuit.

3. 3

   Use a multimeter to check the resistance across the terminals of the Low Temperature Coolant Pump actuator. If the reading shows infinite resistance (OL), the actuator's internal coil is broken/defective.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical shorts.

2. 2

   Access the Pump

   Locate the Low Temperature Coolant Pump actuator on the engine.

3. 3

   Wiring Repair (If Applicable)

   If the diagnostic checks revealed a broken wire or damaged connector, repair the wiring harness or replace the pigtail connector.

4. 4

   Drain Coolant

   If the actuator itself is defective, place a drain pan under the pump and drain the low-temperature coolant circuit.

5. 5

   Remove the Defective Pump

   Disconnect the electrical harness, loosen the hose clamps, remove the coolant hoses, and unbolt the pump actuator from its mounting bracket.

6. 6

   Install the New Pump

   Mount the replacement Low Temperature Coolant Pump actuator, reattach the coolant hoses, and secure the hose clamps.

7. 7

   Reconnect and Refill

   Plug the electrical connector back into the actuator. Refill the low-temperature coolant circuit with the OEM-specified coolant and bleed any air from the system.

8. 8

   Clear Codes

   Reconnect the battery, use a diagnostic tool to clear the 19520 fault code from the Engine ECU, and run the machine to verify the pump operates without triggering the code.