CM2150 Electronic Control System – FAULT CODE 272

  Printable Version

Overview

ISB, ISC and ISL with CM2150 – Fuel Pump Actuator Circuit SMALL | MEDIUM | LARGE

Circuit Description

The circuit is a pulse with modulation (PWM) driver in the electronic control module (ECM) that controls the fuel pump actuator. The actuator is grounded in the ECM. The actuator is normally open. The PWM duty cycle to the fuel pump actuator depends on the difference between desired rail pressure and sensed rail pressure.

Component Location

The fuel pump actuator is located on engine-mounted fuel pump housing. The engine wiring harness and the ECM are other components in the circuit that can cause this fault code. Refer to Procedure 100-002 (Engine Diagrams) in Section F for a detailed component location view.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes

The fuel pump actuator circuit PWM signal is detected to be greater than 0-VDC when the PWM signal is turned off by the ECM.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
• Fuel rail pressure will be higher than the commanded rail pressure.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.

This fault becomes active when the ECM detects an open in the fuel pump actuator circuit. Causes of this fault code are a short circuit to a positive voltage or an open circuit in the fuel pump actuator circuit. If there is high harness resistance or an intermittent open circuit, Fault Code 2311 can have high inactive counts. If the fault code is intermittent, look for causes of an intermittent open circuit such as loose pins and bad connections. If the fault code is intermittent, look closely for loose wire connections at the ECM connector. Also, if the fault code is intermittent, wiggle the harness and the electronic fuel control.

Refer to Troubleshooting Fault Code t05-272