Case IH F-1073-06 - ECU – Engine Control Unit (ECU): Engine compression brake low side ECU driver circuit over temperature failure

The Engine Control Unit (ECU) has detected an over-temperature or over-current condition on the "low side" (the ground-controlled side) of the circuit that operates the engine compression brake actuator. This is typically caused by a short circuit in the wiring, a failed/shorted compression brake solenoid coil drawing too much current, or an internal failure of the ECU's driver.

• MAGNUM AFS Connect
• Case IH 240 Series Axial-Flow® Combines (e.g., 7240, 8240, 9240)
• Case N-Series Tractor Loader Backhoes (TLBs) (e.g., 580N, 580SN, 590SN Tier 4 Final)

1. 1

   Connect the Electronic Service Tool (EST) to determine if the fault is currently active or just a stored intermittent code.

2. 2

   Look for associated circuit codes, such as a short-to-battery or short-to-ground on the compression brake circuit, which should be diagnosed first.

3. 3

   Visually inspect the wiring harness between the Engine ECU and the engine compression brake solenoid for chafed insulation, melted wires, or pinched harnesses.

4. 4

   Disconnect the compression brake solenoid and use a multimeter to measure the resistance across the coil pins. A low resistance reading indicates an internal short in the coil.

5. 5

   Pin out the low-side wire from the ECU connector to the solenoid connector to ensure there is no short to ground along the harness.

1. 1

   Safely Prep the Machine

   Turn off the engine, allow the system fluids and exhaust components to cool, and properly disconnect the battery.

2. 2

   Access the Actuator

   Locate the engine compression brake solenoid/actuator on the engine block/valve cover area.

3. 3

   Disconnect and Isolate

   Unplug the electrical connector to the compression brake solenoid.

4. 4

   Component Replacement (If Failed)

   If the multimeter test during diagnosis revealed an out-of-spec (shorted) solenoid coil, remove the retaining hardware and replace the engine compression brake solenoid with a new OEM unit.

5. 5

   Harness Repair (If Failed)

   If the solenoid tests within specification, the fault lies in the wiring. Repair or replace the damaged section of the low-side wiring harness connecting the ECU to the solenoid.

6. 6

   ECU Replacement (Worst Case)

   If the wiring harness and the solenoid both test perfectly, the internal low-side driver inside the Engine ECU has likely suffered permanent thermal damage. The ECU will need to be replaced and flashed by a dealer.

7. 7

   Reassembly and Clearing

   Reconnect all harnesses and the battery. Use the EST to clear the fault codes, then run the engine and engage the compression brake to verify the repair.