Case IH 3824 – Engine Control Unit (ECU): ENGINE, Throttle Valve Actuator: Short circuit to ground on Out2 TVA Pin A34 error for H-bridge.

The Engine Control Unit (ECU) has detected a short circuit to ground on the output circuit (specifically Pin A34) that controls the Throttle Valve Actuator (TVA). The "H-bridge" refers to the internal circuitry within the ECU that reverses electrical polarity to open and close the electric motor inside the throttle valve. A short to ground on this circuit prevents the ECU from properly controlling the amount of air bypassing the throttle, which can severely impact engine idle and performance.

• Farmall
• SV300
• SR175
• Farmall 95U Pro EP
• Farmall 105U Pro EP
• Farmall 115U Pro EP
• Puma
• Steiger

1. 1

   Ensure the battery is fully charged, then turn the battery quick disconnector to the OFF position before probing sensitive ECU circuits.

2. 2

   Inspect the wiring harness running between the Engine ECU and the Throttle Valve Actuator.

3. 3

   Disconnect the ECU and TVA connectors. Using a multimeter, test the wire corresponding to ECU Pin A34 (Out2) for continuity to ground. If the wire is shorted to the chassis, the harness must be repaired or replaced.

4. 4

   Check the TVA and ECU electrical connectors for moisture, corrosion, or bent pins that could bridge the circuit to ground.

5. 5

   If the wiring harness is intact and not shorted, the internal H-bridge motor of the Throttle Valve Actuator itself has likely failed internally and is shorting to its casing.

1. 1

   Turn the battery quick disconnector to the OFF position (or disconnect the negative battery terminal) to prevent electrical spikes.

2. 2

   Locate the Throttle Valve Actuator (TVA) on the engine's intake air circuit.

3. 3

   Disconnect the electrical connector from the TVA.

4. 4

   Remove the two M6 x 64 bolts from the top of the TVA and the two M6 nuts from the mounting studs.

5. 5

   Remove the intake tube and pull the old Throttle Valve Actuator off the mounting studs.

6. 6

   Remove and discard the old gaskets. Clean the mating surfaces.

7. 7

   Install one new Throttle Valve Actuator (TVA) gasket onto the mounting studs.

8. 8

   Install the new TVA onto the mounting studs.

9. 9

   Install the second new TVA gasket on top of the TVA.

10. 10

    Reinstall the intake tube.

11. 11

    Reinstall the two M6 x 64 bolts and two M6 nuts. Torque them to the manufacturer's specifications.

12. 12

    Reconnect the TVA electrical connector.

13. 13

    Reconnect the battery.

14. 14

    Connect a diagnostic tool (such as the Case IH EST) to clear the 3824 fault code and verify the repair.