Case IH 243 – ENG (Engine Controller / Engine ECU): Error detected in exhaust brake relay.

Triggered when the engine control system detects an electrical anomaly in the exhaust brake relay circuit. The underlying condition is typically an open circuit, a short to ground, or a short to battery voltage in the wiring harness, or a mechanical/electrical failure of the relay itself.

• MX Magnum
• STX Steiger
• Case IH Steiger series
• Case IH Magnum series
• Case IH Puma series
• Case IH Axial-Flow Combines

1. 1

   Verify Power and Ground: Ensure the machine's batteries are fully charged and that the Engine ECU is receiving proper voltage. Low voltage during cranking can cause erratic relay codes.

2. 2

   Locate the Relay: Access the main fuse/relay panel (typically inside the cab on the right-hand console or in the engine compartment) and use the panel diagram to identify the exhaust brake relay.

3. 3

   Inspect the Relay and Socket: Pull the relay and inspect the pins for corrosion, melting, or burn marks. Check the socket for pushed-out pins or debris.

4. 4

   Test the Relay: Use a digital multimeter to test the relay coil resistance. Apply 12V to the coil pins and listen for a solid 'click,' then verify continuity across the switch pins.

5. 5

   Check Fuses: Inspect the fuse associated with the exhaust brake and PTO circuits (e.g., F-036 or similar 5A/7.5A mini fuses).

6. 6

   Harness Continuity Test: If the relay tests good, check the wiring harness between the Engine ECU and the relay socket for chafing, breaks, or shorts to ground.

1. 1

   Disconnect Power

   Turn the ignition key to the OFF position and disconnect the negative battery cable to prevent electrical shorts.

2. 2

   Access the Relay Panel

   Open the fuse/relay access door in the cab or under the hood.

3. 3

   Remove the Faulty Relay

   Grip the exhaust brake relay firmly and pull it straight out of the socket. Do not wiggle it excessively to avoid expanding the socket terminals.

4. 4

   Clean the Contacts

   If there is mild corrosion in the socket, spray it with a quick-drying electrical contact cleaner and let it dry completely.

5. 5

   Install the New Relay

   Align the pins of the new OEM relay with the socket and press it firmly into place until it seats completely.

6. 6

   Restore Power

   Reconnect the negative battery cable.

7. 7

   Clear the Code

   Turn the ignition ON. Use a Case IH EST (Electronic Service Tool) or compatible OBD/CAN diagnostic scanner to clear fault code 243 from the Engine ECU memory.

8. 8

   Operational Test

   Start the engine, bring it to operating temperature, and test the exhaust brake switch to ensure the system engages properly and the code does not return.