Case IH 3954 – Engine Control Unit (ECU) / Engine Management System (EMS): Intake Throttle valve actuator power stage: Open load

An "Open load" error on a power stage means the Engine Control Unit (ECU) is commanding the actuator (the Intake Throttle Valve, which regulates air entering the intake manifold for EGR mixing and smooth engine shutdown) but detects no electrical current flowing through the circuit. This indicates a complete break in the electrical path, which is typically caused by a broken wire, a disconnected or corroded connector, or a completely failed (open) internal motor/coil inside the actuator itself.

• Case IH and New Holland agricultural and construction equipment equipped with FPT (Fiat Powertrain Technologies) engines
• Cummins-equipped models (Tier 3, Tier 4a, and Stage V engines)

1. 1

   Visual Inspection: Check the wiring harness connector at the Intake Throttle Valve (ITV) for loose, corroded, or backed-out pins.

2. 2

   Continuity Test (Harness): Disconnect the ITV and the ECU. Check for an open circuit (continuity test) on the supply and ground/return circuits between the ITV harness connector and the ECU pins.

3. 3

   Actuator Resistance Test: Measure the resistance of the actuator motor/coil directly at the valve's pins to verify it is not open internally.

4. 4

   Short Circuit Check: Ensure there is no short to battery voltage or short to ground on the low-side and high-side power stages of the actuator circuit.

1. 1

   Disconnect Power

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

2. 2

   Harness Repair (If Applicable)

   If the diagnostic checks revealed an open circuit in the wiring, repair the broken wire or replace the damaged connector terminal. If the harness is good, proceed to replace the valve.

3. 3

   Remove the Valve

   Disconnect the electrical connector from the Intake Throttle Valve. Remove the mounting bolts securing the valve to the intake manifold/EGR piping.

4. 4

   Clean Mating Surfaces

   Remove the old valve and thoroughly clean the mating surface on the intake manifold to ensure a proper seal.

5. 5

   Install New Valve

   Install the new Intake Throttle Valve with a new gasket. Torque the mounting bolts to OEM specifications.

6. 6

   Reconnect

   Reconnect the electrical connector and the battery.

7. 7

   Clear Codes and Calibrate

   Connect a diagnostic service tool (such as the CNH EST or Jaltest). Clear the inactive fault codes. Depending on the exact FPT engine generation, you may need to run an actuator test or use the service tool procedure to restore "Self Learning Parameters" so the ECU learns the end-stops of the new throttle valve.