Case IH 3673 – Engine Control Unit (ECU): EGR Valve Circuit - Short Circuit Overload Error For H-Bridge

The H-bridge driver circuit has detected an excessive current draw, typically caused by a short circuit in the wiring harness, an internal short within the EGR valve actuator motor, or a failure within the control module's internal H-bridge driver.

• Farmall
• skid steer
• SR175
• SR240B
• TR320

1. 1

   Visually and electrically inspect the wiring harness between the Engine Controller (ECU) and the EGR valve for chafed insulation, pinched wires, or shorts to ground/other wires.

2. 2

   Disconnect the EGR valve and the ECU to inspect the pins on both connectors for corrosion, water intrusion, or bent pins.

3. 3

   With the EGR valve disconnected, use a multimeter to check the resistance across the EGR valve motor pins (extremely low resistance indicates an internal short).

4. 4

   Clear the fault codes using a diagnostic service tool to test the ECU H-Bridge; if the code returns immediately upon EGR actuation, the H-bridge driver is likely fried.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable.

2. 2

   Repair Wiring

   If a short is found in the harness, repair the damaged wires using OEM-approved splicing techniques and heat-shrink tubing, or replace the affected harness section.

3. 3

   Replace the EGR Valve

   If the EGR valve motor is internally shorted, remove the mounting hardware and gaskets, extract the old EGR valve, and install the new unit with fresh gaskets.

4. 4

   Replace the Engine Controller

   If the wiring and EGR valve are fully functional, the ECU must be replaced due to internal H-bridge failure.

5. 5

   Restore Self-Learning Parameters

   Connect the appropriate Case IH diagnostic service tool and run the procedure to restore the engine's self-learning parameters and calibrate the new EGR valve position.