Case IH 3958 – Engine Control Unit (ECU): Intake Throttle Valve Actuator Short Circuit to Ground

The fault code indicates an electrical malfunction in the Intake Throttle Valve (ITV) actuator circuit, specifically a short circuit to ground on the power stage of the actuator, preventing the control module from properly regulating the intake throttle valve.

• Magnum series
• Steiger series
• T8.320
• T8.350
• T8.380
• Maxxum Series (CVT/TMR)
• Puma Series
• 7R/8R/9R series equivalents
• Axial-Flow combines
• 150 series
• AFX8010

1. 1

   Inspect the intake and exhaust systems for any physical restrictions, blockages, or damage.

2. 2

   Inspect the engine wiring harness and the connector at the Intake Throttle Valve for signs of damage, water ingress, corrosion, or loose pins.

3. 3

   Disconnect the harness and use a multimeter to measure the continuity between the pins on the vehicle wiring harness and the ECU. Test the power and ground circuits for a short circuit to ground or an open load.

4. 4

   If the wiring is intact, use a diagnostic tool to perform an Actuator Test. Command the Intake Throttle Valve Actuator to 30%, 60%, and 90% duty cycles. The actual value should be within +/- 2% of the commanded value. If not, the actuator is internally faulty.

1. 1

   Preparation

   Ensure the ignition key is ON (or OFF depending on the manual's safety spec for harness disconnection), vehicle speed is 0 km/h, and engine speed is 0 rpm. Disconnect the battery negative terminal to prevent electrical spikes.

2. 2

   Repair wiring harness

   If the multimeter test revealed a short to ground in the wiring harness between the ECU and the actuator, repair the damaged section of the wire or replace the engine wiring harness.

3. 3

   Replace Intake Throttle Valve Actuator

   If the wiring tests good, the Intake Throttle Valve Actuator has an internal short and must be replaced. Disconnect the electrical connector, remove the mounting hardware, remove the faulty valve, and clean the mating surface. Install the new valve, torque the mounting hardware to OEM specifications, and reconnect the electrical connector.

4. 4

   Clear fault codes

   Reconnect the battery. Use a diagnostic tool to clear the fault codes from the ECU memory.

5. 5

   Validate repair

   Perform a maximum of 4 driving cycles or run the Actuator Test again via the diagnostic tool to ensure the Check Engine Light (CEL) remains off and the valve responds correctly.