Case IH 3669 – Engine Control Unit (ECU / EDC): Short circuit to battery on Out1 error for H-bridge

This code indicates that the engine controller has detected a short circuit to a battery voltage source on the Exhaust Gas Recirculation (EGR) valve circuit. Specifically, the fault is traced to the 'Out1' circuit, which corresponds to pin A50 on the engine controller's 60-pin connector.

• Farmall
• Farmall series tractors
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• Compact wheel loaders

1. 1

   Visually inspect the wiring harness running between the Engine ECU and the EGR valve for chafing, melted insulation, or pinched wires that could expose the copper to a 12V power source.

2. 2

   Disconnect the 60-pin connector at the Engine ECU and the connector at the EGR valve, then use a multimeter to test the wire corresponding to pin A50 (EGR Out1) for continuity to battery voltage.

3. 3

   Verify if there are accompanying CAN bus fault codes, as multiple communication codes may indicate a broader electrical system or CAN bus failure rather than an isolated EGR short.

4. 4

   If the wiring harness tests good (no short to battery), suspect an internal short in the H-bridge motor/actuator inside the EGR valve itself.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical damage during testing and repair.

2. 2

   Isolate the Short

   Based on the diagnostic pin testing, determine if the short is in the wiring harness or the EGR valve actuator.

3. 3

   Repair Wiring

   If the wire for pin A50 is shorted to power, locate the damaged section of the harness. Repair the wire using proper weatherproof splices, or replace the affected harness section.

4. 4

   Replace EGR Valve

   If the harness is intact, the EGR valve actuator has failed internally. Remove the faulty EGR valve and install the replacement unit.

5. 5

   Reassemble and Reconnect

   Reconnect all electrical connectors and the battery.

6. 6

   Software Reset

   Connect the appropriate diagnostic service tool (e.g., CNH Electronic Service Tool). Clear the fault codes. If the EGR valve was replaced, you must run the 'Reset ECU data (EGR valve)' configuration procedure to restore the engine controller's self-learning parameters.

7. 7

   Verify Repair

   Start the engine and verify that fault code 3669 does not return.