Cummins ISB CM850 (2003-06) Fault Code: 2266 PID: SID 126 SPN: 1075 FMI: 4 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.

Cummins ISB CM850 (2003-06) Fault Code: 2266 PID: SID 126 SPN: 1075 FMI: 4 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.

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 short circuit to ground or low resistance.

On 12 VDC Automotive and 24 VDC Industrial or Marine systems 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 also become active if the lift pump rotor stalls or seizes. When the fault conditions are 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 keyswitch ON, and if the cause is no longer present, the fault code will become inactive and can be cleared.

On 24 VDC Automotive systems, the ECM driver to the lift pump relay is turned off when a short circuit to ground or high current in the electric fuel lift pump wiring harness relay circuit is detected. Causes of this fault code are a short circuit to ground or high current in the electric fuel lift pump wiring harness, relay or engine harness. This fault code will not become active if the voltage regulator or electric fuel lift pump has failed.

NOTE: On 12 VDC systems, 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.

Possible repairs:

1)Replace the electric fuel lift pump relay.
2)Removal and installation of the connector may correct the problem.
3)Repair or replace the engine harness.
4)Replace the ECM.