Case IH F-1073-03 - ECU – Engine Control Unit (ECU): Engine compression brake low side driver circuit short to battery failure

The ECM controls the engine compression brake solenoids using a Pulse Width Modulated (PWM) signal. This code triggers when the ECM detects system voltage (a short to the battery) on the engine brake #2 circuit when the PWM signal is commanded to be turned off. When this fault is active, the ECM will illuminate the amber Check Engine light and disable the engine brake circuit to prevent damage.

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1. 1

   Verify that the ECU calibration is up to date and check the calibration revision history for any applicable software fixes.

2. 2

   Inspect the engine brake solenoid signal circuit connectors (2-pin or 4-pin Weather Pack near the injector pass-through connector) for pushed-out pins, moisture, or corrosion.

3. 3

   With the keyswitch OFF, disconnect the engine brake harness and the Under Valve Cover (UVC) connectors, then use a multimeter to check the engine brake #2 signal wire for a short circuit to battery voltage.

4. 4

   Use the electronic service tool (such as CNH EST) to run a Device check or automated engine brake actuator test to see if the solenoid responds or immediately shorts out.

1. 1

   Power Down

   Turn the keyswitch to the OFF position and disconnect the battery ground cable to ensure safety while working on the engine wiring.

2. 2

   Isolate the Short

   Disconnect the main engine harness from the engine brake pass-through connector on the rocker lever housing.

3. 3

   Test the External Harness

   Test the external wiring harness for a short to the battery. If a short is found in the external harness, repair the chafed wire or replace the harness section.

4. 4

   Access the Solenoids

   If the external harness tests good, the short is likely under the valve cover. Remove the engine valve cover to access the internal jumper harness and the engine brake solenoids.

5. 5

   Test the Internal Components

   Disconnect the internal jumper harness from the engine brake solenoid #2 (which typically controls the rear bank of cylinders, e.g., cylinders 4, 5, and 6). Test the solenoid for an internal short.

6. 6

   Replace Faulty Parts

   If the solenoid is internally shorted, replace the engine brake actuator/solenoid. If the internal jumper harness is melted or chafed, replace the harness.

7. 7

   Reassembly

   Reinstall the valve cover using a new valve cover gasket. Reconnect all external electrical connectors.

8. 8

   Clear Codes

   Reconnect the battery, turn the keyswitch ON, and use the electronic service tool to clear the fault code. Run the engine and verify that the amber Check Engine light remains off and the engine brake functions normally.