New Holland ENG 3673 – Engine Control Unit (ECU): EGR Short Over Load Error for H-bridge

The ECU has detected an excessive current draw (overload) or a short circuit to ground/battery on the EGR valve motor circuit (specifically on pins A35 or A50). This condition is typically caused by a mechanically jammed EGR valve (often due to heavy carbon buildup), an internally shorted EGR actuator motor, or a damaged wiring harness.

• L220
• L225
• L230
• L316
• L318
• L320
• L328
• C232
• C238
• C327
• C330
• C345
• B90B
• B95C
• B100B
• B110C
• T4 Series (e.g., T4.55)
• TD5.115

1. 1

   Inspect the wiring harness from the Engine ECU to the EGR valve. Look for chafing, abrasion, corrosion, or incorrect attachment that could cause a short to ground or short to battery.

2. 2

   Disconnect the EGR valve and ECU connectors. Ensure all pins (especially ECU pins A35 and A50) are secure, tight, and free of corrosion or moisture.

3. 3

   Remove the EGR valve and inspect it for heavy soot or carbon buildup. A valve that is mechanically stuck closed or open will cause the actuator motor to draw excessive current, triggering the H-bridge overload fault.

4. 4

   Test the resistance of the EGR valve motor pins to determine if the actuator itself has suffered an internal short circuit.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Access the EGR Valve

   Locate the EGR valve on the exhaust/intake manifold assembly of the F5C/F5H engine.

3. 3

   Disconnect Wiring

   Unplug the electrical connector from the EGR valve actuator.

4. 4

   Remove the EGR Valve

   Remove the mounting bolts securing the EGR valve to the manifold. Carefully remove the valve and discard the old metal gasket.

5. 5

   Inspect and Clean

   Inspect the manifold ports for excessive carbon buildup and clean them carefully without dropping debris into the engine. If the old EGR valve is heavily carbon-fouled but electrically sound, a thorough cleaning with EGR solvent might unstick it. However, if the motor is internally shorted (which is common with code 3673), it must be replaced.

6. 6

   Install New Part

   Install the new EGR valve using a new OEM gasket. Torque the mounting bolts to the manufacturer's specifications.

7. 7

   Reconnect and Reassemble

   Reconnect the EGR electrical harness and the battery.

8. 8

   Clear Codes

   Connect a diagnostic tool (such as the CNH Electronic Service Tool) to the machine, clear the inactive ENG 3673 fault code, and run the engine to verify the code does not return.