New Holland 3669 – ECU: EGR H-Bridge Out1 Short to Battery

The Engine Control Unit (ECU) has detected a short circuit to the battery (positive voltage source) on the first output channel (Out1) of the H-bridge circuit. This circuit controls the Exhaust Gas Recirculation (EGR) valve. A short to battery means the circuit is receiving continuous voltage when it should not be, which can cause improper operation or damage to the EGR system and affected circuits.

• CR6.80
• CR7.90
• CR8.90
• CR10.90
• CX8.80
• CX8.90
• FR series
• Roll-Belt 450
• Roll-Belt 460
• Roll-Belt 550
• Roll-Belt 560
• Pro-Belt series
• 5150
• 6150
• 7130
• 7150
• 7230
• 7240
• 7250
• 8230
• 8240
• 8250
• 9230
• 9240
• 9250
• RB455
• RB465
• RB565

1. 1

   Check for any blown fuses related to the ECU or engine systems

2. 2

   Visually inspect the wiring harness and connectors between the ECU, the H-bridge module, and the EGR valve for chafed or melted insulation, corrosion, or loose pins

3. 3

   Use a diagnostic tool (like New Holland EST) to verify code 3669 and check for related EGR or H-bridge codes (e.g., 3670, 3671, 3672)

4. 4

   Disconnect the EGR valve, clear codes, and operate the machine to see if the fault returns (this isolates the valve from the wiring)

5. 5

   With the relevant components disconnected, use a multimeter to test the 'Out1' wire (ECU pin A50) for continuity to the battery positive terminal (there should be no continuity) and check for shorts to other wires

1. 1

   Isolate and replace EGR valve

   Disconnect the EGR valve from the harness. Clear the fault codes and operate the machine. If the fault does not return, the short is internal to the EGR valve. Replace the EGR valve.

2. 2

   Repair wiring harness

   If the fault persists with the EGR valve disconnected, test the Out1 wire (ECU pin A50) for a short to battery positive or other wires. Repair or replace the affected section of the harness if damaged.

3. 3

   Replace H-bridge module

   If the wiring and EGR valve test good, the H-bridge module is the likely cause. Replace the sealed H-bridge module, clear fault codes, and perform a system test to verify the repair.