Case IH 4257 – Engine ECU (MCM): Injector Amplifier Control Valve Short-circuit

Indicates an electrical failure in the fuel injection system. Specifically, a short-circuit to battery (FMI 3) or short-circuit to ground (FMI 4) on the Injector Amplifier Control Valve for Cylinders #1, #2, and #3 (or #4, #5, and #6).

• MAXXUM T4E
• VESTRUM CVX
• Case IH Maxxum series (110 EP to 140 EP)

1. 1

   Check the fuel level and inspect for contaminated fuel (Injector fault cause).

2. 2

   Inspect the intake system and fuel system for restrictions, leaks, or physical damage (Injector fault cause).

3. 3

   Check the engine oil level and inspect for oil contamination (Injector fault cause).

4. 4

   Test the injector circuit wiring harness for continuity, specifically looking for a short to the battery or a short to ground on the amplifier control valve circuit (Injector fault cause).

5. 5

   Use a hydraulic pressure gauge to check the system pressure at various test points and consult the service manual for correct specifications (Hydraulic fault cause).

6. 6

   Inspect the Hydraulic Oil Filter Restrict Pressure Switch for damage or shorted wiring (Hydraulic fault cause).

7. 7

   Inspect hydraulic cylinders and rods for external leaks or worn seals (Hydraulic fault cause).

1. 1

   Address Wiring/Electrical Shorts

   Trace the wiring harness from the Engine ECU (MCM) to the Injector Amplifier Control Valve for the affected cylinder bank. Repair or replace any chafed wires causing the short to ground or battery.

2. 2

   Replace the Control Valve/Injector

   If the wiring is intact, the internal solenoid of the Injector Amplifier Control Valve has failed and the injector/valve assembly must be replaced.

3. 3

   Hydraulic System Repair

   If the hydraulic pressure gauge confirms low pressure, suspect a failing hydraulic pump. Remove the pump, replace the Hydraulic Pump Mounting Gasket, and install a new or rebuilt pump. If the pressure is fine but the switch reads an unexpected value, replace the Hydraulic Oil Filter Restrict Pressure Switch.