Case IH 393 – ENG: Engine Brake driver 3 circuit failure

The Engine Control Module (ECM) has detected low voltage at engine brake circuit 3. The underlying condition is typically caused by the engine brake circuit 3 being shorted to ground or experiencing an open circuit.

• MX Magnum
• STX Steiger
• Case IH Steiger tractors
• Case IH Magnum tractors
• Case IH Puma tractors
• Case IH CVX tractors

1. 1

   Inspect engine brake circuit 3 for a short to ground

2. 2

   Verify the voltage at the engine brake circuit 3, as the ECM triggers this code when it detects abnormally low voltage

3. 3

   Inspect the wiring harness routing from the ECM to the valve cover pass-through connector for chafing, melting, or corrosion

4. 4

   Check if the code is active or stored (diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running)

1. 1

   Access the Circuit

   Locate the engine brake wiring harness. If external harness checks pass, remove the valve cover to access the internal engine brake actuators.

2. 2

   Test the Actuator

   Test the resistance of the engine brake actuator for driver 3 to ensure it is not internally shorted.

3. 3

   Repair/Replace

   Repair any shorted wiring in the harness or replace the faulty engine brake actuator solenoid.

4. 4

   Validate the Repair

   To clear the code and validate the repair, perform a key cycle, start the engine, and let it idle for 1 minute.

5. 5

   Clear Codes

   Use an electronic service tool (or the "Reset All Faults" command) to clear the inactive faults from the ECM memory.