New Holland ENG 243 – Engine Controller (Engine ECU / ECM): Error detected in exhaust brake relay

The engine control system has detected an electrical fault (such as an open circuit, short to ground, or short to power) in the exhaust brake relay enable circuit, often traced to pin 42 of the engine harness. As a result, the exhaust brake will not function.

• tractors
• combines
• forage harvesters

1. 1

   Use a diagnostic tool to verify ENG 243 is active and check for any other related voltage or sensor codes that might indicate a broader harness issue.

2. 2

   Locate the exhaust brake relay in the machine's main fuse/relay panel.

3. 3

   Inspect the wiring harness connecting the Engine ECU to the exhaust brake relay, paying special attention to the circuit connecting to pin 42 of the engine harness. Look for chafed wires, broken connections, or corrosion.

4. 4

   Remove the exhaust brake relay and test it for proper internal resistance. Apply voltage to the coil pins to see if the relay clicks and the switch contacts close properly.

5. 5

   Verify that the relay socket is receiving the correct ignition power and that the ECM is capable of providing the ground/control signal.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent electrical shorts during repair.

2. 2

   Access the Relay Panel

   Open the electrical distribution box where the exhaust brake relay is housed.

3. 3

   Remove and Inspect

   Pull the exhaust brake relay. Inspect the relay terminals and the socket for signs of melting, burning, or severe corrosion.

4. 4

   Repair Wiring

   If the diagnostic checks revealed a broken or shorted wire between the relay panel and pin 42 of the engine ECM, repair the wire using proper soldering and heat-shrink techniques, or replace the damaged harness section.

5. 5

   Replace the Relay

   If the wiring is intact but the relay failed the bench test (or if the socket shows heat damage from a failing relay), install a new exhaust brake relay.

6. 6

   Reassemble and Clear Codes

   Reconnect the battery, turn on the ignition, and use a diagnostic tool to clear the ENG 243 fault code.

7. 7

   Test Operation

   Run the engine and test the exhaust brake functionality to ensure the code does not return.