Case IH P14 – Engine ECU: Test Shut Off Paths, Shorted To High Source

The engine's electronic control system has detected a short circuit to a high voltage source (such as battery positive, B+) in the fuel shut-off or test shut-off circuitry. This prevents the controller from properly regulating or verifying the fuel shut-off valve.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Turn the keyswitch OFF and disconnect the battery or pull the relevant ECU fuse to prevent false multimeter readings.

2. 2

   Disconnect the wiring harness connectors at both the Engine ECU and the fuel shut-off solenoid to isolate the circuit.

3. 3

   Visually inspect the outer covering of the engine wiring harness for rubbing, melting, or chafing that could cause a wire to short against a power source.

4. 4

   Using a multimeter set to Ohms, probe the shut-off signal wire against all known power supply pins (B+) in the harness. A low resistance reading indicates a short to high voltage.

5. 5

   Check the internal resistance of the fuel shut-off solenoid itself to ensure it hasn't failed internally and shorted out.

1. 1

   Locate the short

   Trace the wiring harness from the fuel shut-off solenoid back to the Engine ECU.

2. 2

   Repair the harness

   If a short to a high-voltage wire is found in the harness, cut out the damaged section. Splice in new wiring of the same gauge using a manufacturer-approved harness repair kit (weather-sealed crimps or solder with heat shrink).

3. 3

   Replace the solenoid

   If the wiring harness tests perfectly fine, the short to high source is likely internal to the fuel shut-off solenoid. Unbolt the old solenoid from the injection pump, install the replacement, and plug it into the harness.

4. 4

   Reassemble and clear codes

   Reconnect all ECU and solenoid connectors. Reconnect the battery, turn the key ON, and use a diagnostic service tool to clear the T14 fault code. Start the engine to verify the code does not return.