Case IH 396 – Engine Control Module (ECM): Rear Fueling current is too low.

The Engine Control Module (ECM) has detected a low current or an open circuit at the rear fueling actuator circuit. The engine will enter a protection 'limp mode' and run using only the front three cylinders, resulting in a severe loss of engine power and performance.

• MX Magnum
• STX Steiger
• MX240
• MX255
• MX270
• MX285
• STX275
• STX325
• 8780

1. 1

   Inspect the engine wiring harness connecting the ECM to the CAPS pump rear fueling actuator for chafed wires, breaks, or corrosion.

2. 2

   Measure the resistance of the rear fueling actuator coil on the CAPS pump to check for internal coil failure.

3. 3

   If the pump housing allows, swap the front and rear fueling actuators and run a cylinder performance test to determine if the fault follows the actuator or remains on the rear circuit.

1. 1

   Disconnect Power

   Always disconnect the batteries (negative cable first) before performing service on the engine electrical or fuel system.

2. 2

   Harness Repair

   If the diagnostic tests revealed an open circuit or short in the wiring harness, repair or replace the damaged section of the harness.

3. 3

   Pump Replacement

   If the rear fueling actuator has failed, replace the entire CAPS fuel injection pump assembly, as the internal CAPS actuators are typically not serviced separately.

4. 4

   Remove the CAPS Pump

   Disconnect the electrical connectors to the fueling actuators. Remove the high-pressure fuel lines, supply lines, and mounting hardware from the CAPS pump.

5. 5

   Install the New Pump

   Install the remanufactured CAPS pump (or an aftermarket Bosch P-pump conversion kit).

6. 6

   Reconnect and Torque

   Reconnect all fuel lines, ensuring proper torque specifications to avoid high-pressure leaks. Reconnect the electrical harness.

7. 7

   Prime the System

   Reconnect the batteries. Prime the fuel system using the lift pump. Do not pre-fill the fuel filter directly, as this can introduce unfiltered contaminants into the new pump.

8. 8

   Clear Codes

   Start the engine and let it idle for 1 minute. Verify that the fault code status changes to INACTIVE and the Check Engine light turns off. Use a diagnostic tool to clear the inactive faults.