Case IH 3823 – Engine Control Unit (ECU): Short circuit to ground on Out1 error for H-bridge

A short circuit to ground on the Throttle Valve Actuator (TVA) circuit, triggered when the ECU detects a short to ground on Output 1 (specifically Pin A49 on the 60-pin engine harness connector).

• Farmall
• Magnum
• Puma
• SV300

1. 1

   Visually inspect the wiring harness running between the Engine ECU and the Throttle Valve Actuator (TVA) for chafing, melting, or pinched wires that could cause a short to the chassis ground.

2. 2

   Disconnect the 60-pin engine connector at the ECU and the connector at the TVA to check for moisture, corrosion, or bent pins (specifically Pin A49).

3. 3

   Using a multimeter, test the wire corresponding to ECU Pin A49 for continuity to ground. If continuity exists while both ends are unplugged, the harness is shorted.

4. 4

   Test the Throttle Valve Actuator pins for an internal short to ground.

5. 5

   If the wiring and the actuator test fine, verify if the internal H-bridge driver inside the ECU has failed.

1. 1

   Turn off the ignition key and disconnect the negative battery cable to prevent electrical damage.

2. 2

   Disconnect the wiring harness from the Throttle Valve Actuator and the 60-pin connector from the Engine ECU.

3. 3

   Probe Pin A49 on the harness side with a multimeter set to ohms/continuity. Connect the other lead to a known good chassis ground.

4. 4

   If a short to ground is found, trace the harness back from the actuator to the ECU, open the loom, and repair the damaged wire using OEM-approved splicing methods.

5. 5

   If the harness is intact, test the TVA for an internal short. If faulty, unbolt the Throttle Valve Actuator body from the intake manifold and install a replacement unit.

6. 6

   Reconnect all electrical connectors and the battery.

7. 7

   Connect the Electronic Service Tool (EST) to the machine's diagnostic port, clear the inactive fault codes, and cycle the key to verify that code 3823 does not return.