Case IH 3818 – Engine Control Unit (ECU): Throttle Valve Actuator (TVA) Circuit - Open Load Error For Power Stage

The engine's control module has detected an open circuit (a complete break in the electrical path) in the power stage (H-bridge) circuit that supplies voltage to the Throttle Valve Actuator. Because of the open load, the controller cannot electronically actuate the valve to regulate intake airflow.

• Farmall
• skid steer
• Small and medium-frame Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• Farmall 95U
• Farmall 105U
• Farmall 115U Pro EP

1. 1

   Inspect the wiring harness running between the Engine ECU and the Throttle Valve Actuator for chafing, cuts, or broken wires.

2. 2

   Disconnect and inspect the electrical connector at the TVA and the 60-pin connector at the Engine ECU (specifically pins A34 and A49) for backed-out pins, corrosion, or moisture.

3. 3

   Using a multimeter, test the continuity of the power stage wires from the ECU 60-pin connector to the TVA connector to rule out a broken wire in the harness.

4. 4

   Measure the internal resistance of the Throttle Valve Actuator itself. If the meter reads out of limits (OL) or infinite resistance, the open circuit is internal to the actuator solenoid.

1. 1

   Turn off the machine's ignition and disconnect the negative battery cable.

2. 2

   Locate the Throttle Valve Actuator (TVA) on the engine intake tube.

3. 3

   Disconnect the electrical connector from the TVA and the air pressure/temperature sensor.

4. 4

   If diagnostic testing proved the wiring harness is intact and the open load is internal to the actuator, proceed with replacement.

5. 5

   Remove the mounting bolts securing the TVA and intake tube.

   Typically torqued to 20 - 30 N·m / 15 - 22 lb ft.

6. 6

   Remove the faulty Throttle Valve Actuator.

7. 7

   Install the new TVA and reinstall the intake tube.

   Torque the bolts to 20 - 30 N·m (15 - 22 lb ft).

8. 8

   Reconnect the TVA electrical connector and the battery.

9. 9

   Connect a diagnostic tool to clear the stored 3818 fault code and run the engine to verify the repair.