Electric Lift Pump for Engine Fuel Supply Circuit – Voltage Below Normal or Shorted to Low Source
|Fault Code: 2266
Electric Lift Pump for Engine Fuel Supply Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at the fuel lift pump circuit.
Engine can be difficult to start.
ISC and ISL with CM2150 – Electric Fuel Lift Pump Circuit
The circuit is a pulse width modulated driver in the electronic control module (ECM) that controls the electric fuel lift pump. The lift pump is grounded in the ECM and runs at 100-percent duty cycle for approximately 30 seconds at key-on.
The electric fuel lift pump is located behind the ECM cooling plate on the intake side of the engine, near the front. Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view.
Conditions for Running the Diagnostics
This diagnostic runs when the keyswitch is in the ON position.
Conditions for Setting the Fault Codes
The engine fuel lift pump circuit pulse width modulated signal is detected to be 0-VDC when the pulse width modulated signal is turned on by the ECM and should be at system voltage.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
- The engine fuel lift pump will be disabled.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light and the fault code state will become inactive immediately after the diagnostic runs and passes. The fault code can also be cleared with INSITE™ electronic service tool.
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 code becomes active whenever the ECM detects a short circuit to ground or high current in the electric lift pump circuit. Causes for this fault code are a short circuit to ground or low resistance
(lift pump partially shorted). During cold weather, gelled fuel can plug the lift pump and cause this fault code. Listen to the lift pump to be sure it is running during cold ambient temperatures (less than -29°C [-20°F]). This fault code can possibly also become active if the lift pump rotor stalls or seizes. When the fault condition is detected, the ECM driver to the lift pump is turned off to protect the circuit. It is necessary to cycle the keyswitch OFF and then back ON before the ECM will retest for the cause of the fault code. The ECM driver is re-enabled at key-on. If the cause if no longer present, the fault code will become inactive and can be cleared.
Note: This fault code will also become active if the priming pump motor stalls. Stall current for the priming pump motor is approximately 9 amperes. A good priming pump typically runs with less than 3 amperes. If the fault code is intermittent, observe the snapshot data priming pump measured current. If current was near 9 amperes when the fault condition occurred, conclude that the rotor has stalled and replace the electric priming pump.