Case IH 338 – ENG (Engine Controller / ECM): Idle Shutdown Vehicle Accessory Relay Voltage is too high

Indicates that the Idle Shutdown Vehicle Accessory Relay Voltage is too high. This typically points to an electrical problem such as a short to battery voltage or an open circuit on the ground side of the relay control circuit. Operators may experience the machine refusing to move while the engine is running due to electrical safety lockouts.

• MX Magnum
• STX Steiger
• Magnum 215
• Magnum 225
• Magnum 245
• Magnum 250
• Magnum 275
• Magnum 280
• Magnum 305
• Magnum 310
• Magnum 335
• MX Series Tractors
• TG Series Tractors
• CR9090 Combine
• CX8080 Combine
• CX8090 Elevation Tier 4A Combine

1. 1

   Check the Idle Shutdown Vehicle Accessory Relay and its socket for corrosion, pushed-out pins, or melted plastic.

2. 2

   Test the relay control circuit between the Engine ECM and the relay block for a short to a 12V power source or a broken ground wire.

1. 1

   Verify the Symptom

   Confirm the presence of active code ENG 338 on the instrument cluster or diagnostic service tool.

2. 2

   Inspect the Relay

   Locate the Idle Shutdown Vehicle Accessory Relay in the machine's power distribution center. Check the relay and its socket for corrosion, pushed-out pins, or melted plastic.

3. 3

   Circuit Testing

   Use a multimeter to test the relay control circuit between the Engine ECM and the relay block. You are looking for a short to a 12V power source (which triggers the 'voltage is too high' fault) or a broken ground wire.

4. 4

   Component Replacement

   If the wiring harness tests good, the relay itself may have an internal short. Replace the relay with a known good OEM part.

5. 5

   Clear Codes

   Reconnect battery power, cycle the key, and use a diagnostic tool to clear the power-down cycle data and ensure the code does not return.