Caterpillar C9 Engine 15 164-2 Injector Operating Pressure Signal Unstable

Problem: The Engine Control Module (ECM) has detected an issue with the injector operating pressure signal. This issue is triggered under the following conditions:

1. Engine Off Condition:
   • The injector operating pressure exceeds 3 MPa (435 psi) for more than 3 seconds.
2. Engine Running Condition:
   • The difference between the actual and desired injector pressure exceeds 2 MPa (290 psi) for more than 10 seconds.
   • The actual rail pressure is between 11.0 MPa (1595.41 psi) and 17.4 MPa (2523.66 psi) for more than 10 seconds.
   • The sensor current changes by more than 0.075 amps, and the rail pressure changes by less than 0.5 MPa (72.5 psi).
3. Additional Conditions:
   • With the engine not running and power applied to the ECM for at least 4 seconds, cold mode is not active.
   • Engine speed is at 0 rpm for more than 3 seconds, and the engine is not running.

Description: The injector actuation pressure sensor monitors the oil pressure in the high-pressure oil distributor. This oil pressure is crucial for both actuating the injectors and regulating the fuel injection pressure. The Engine Control Module (ECM) uses input from this sensor to calculate the fuel injection pressure, and it controls the injector actuation pressure control valve based on this data.

Caterpillar C9 Engine Diagnostics:

• ECM: Caterpillar C9 Engine Control Module
• Diagnostic Tool: Caterpillar CAT ET 2024C
• Communication Adapter: CAT Communications Adapter 3

Possible Causes:

1. ECM Connector Issues:
   • Loose, corroded, or damaged ECM connector could result in unstable pressure readings.
2. Injector Actuator Pressure Sensor Fault:
   • A malfunctioning or damaged pressure sensor may be sending incorrect data to the ECM, leading to unstable pressure signals.
3. Wiring or Connection Problems:
   • Open circuits, loose connections, or short circuits in the wiring between the sensor and ECM may cause inaccurate pressure readings.

Next Steps:

1. Inspect the ECM connector for any signs of wear, corrosion, or damage.
2. Test the injector actuator pressure sensor for proper functionality.
3. Check the wiring and connections from the sensor to the ECM to ensure there are no loose, damaged, or corroded connections.