Case IH 3821 – Engine Control Unit (ECU): Throttle Valve Actuator (TVA) Circuit - Short Circuit To Battery (A = 60pin Connector - Engine; A49) / Short circuit to battery on Out1 error for H-bridge.

The engine's computer has detected that the voltage on the output circuit 1 (Out1) controlling the Throttle Valve Actuator is shorted to battery voltage. The short is specifically traced to pin A49 on the 60-pin engine harness connector.

• Farmall
• SV300
• SR175
• Compact Track Loaders (CTLs)
• Farmall 95U
• Farmall 105U
• Farmall 115U Pro EP
• Steiger
• Puma

1. 1

   Visually inspect the wiring harness running from the Engine ECU to the Throttle Valve Actuator (TVA) for chafing, melted insulation, or pinch points that could expose the wire to a 12V power source.

2. 2

   Disconnect the 60-pin connector at the Engine ECU and the connector at the TVA. Inspect pin A49 on the ECU side and the corresponding pin on the TVA connector (often labeled X-9001) for corrosion, moisture, or bent pins.

3. 3

   With both ends disconnected, use a digital multimeter to test the wire corresponding to pin A49 for a short to battery voltage. Turn the key ON (engine OFF) and probe the wire; if voltage is present, the harness is shorted to a power wire.

4. 4

   If the harness tests good, check the Throttle Valve Actuator's solenoid/motor for an internal short circuit.

1. 1

   Turn off the machine, remove the key, and disconnect the negative battery cable.

   This prevents electrical spikes.

2. 2

   If the diagnostic tests revealed a short in the wiring harness, locate the damaged section of the harness. Repair the wire for pin A49 using proper soldering and heat-shrink techniques, or replace the engine wiring harness if the damage is extensive.

3. 3

   If the harness is intact and the TVA is internally shorted, locate the Throttle Valve Actuator on the engine's air intake manifold.

4. 4

   Disconnect the electrical connector from the TVA.

5. 5

   Remove the mounting bolts securing the TVA to the intake piping/manifold.

6. 6

   Remove the old TVA and clean the mating surface on the intake.

7. 7

   Install the new Throttle Valve Actuator with a new gasket/seal (if applicable) and torque the mounting bolts to OEM specifications.

8. 8

   Reconnect the TVA electrical connector and the 60-pin ECU connector.

9. 9

   Reconnect the battery.

10. 10

    Connect a diagnostic scan tool to the machine, clear the inactive 3821 fault code, and run the engine to verify the code does not return and that the engine idles correctly.