Cummins ISX12 CM2250 (2010-12) Fault Code: 2266 (MR) PID: SID 126 SPN: 1075 FMI: 4 Electric Lift Pump for Engine Fuel Supply Circuit- Voltage Below Normal or Shorted to Low source

Circuit Description
The fuel lift pump circuit is a discrete output in the electronic control module (ECM) that controls the electric fuel lift pump. The lift pump is grounded in the ECM.

Component Location
The electric fuel lift pump is located behind the ECM cooling plate on the intake side of the engine.

Conditions for Running the Diagnostics
This diagnostic runs during the first 1 minute after initial key ON, when the fuel lift pump is being commanded to run.

Conditions for Setting the Fault Codes
The engine fuel lift pump signal circuit is detected to be 0-VDC when the signal is turned ON by the ECM and must be at system voltage.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
The engine fuel lift pump will be disabled.
Conditions for Clearing the Fault Code
Perform a key cycle, and leave the key switch in the ON position for at least 2 minutes.
The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
The Reset All Faults command in INSITE? electronic service tool can be used to clear active and inactive faults.

Shop Talk
This fault code becomes active whenever the ECM detects a short circuit to ground or high current in the electric fuel 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 is no longer present, the fault code will become inactive and can be cleared.

Possible Cause:
1) Electric Fuel Lift Pump failure
2) Engine Harness
3) ECM failure