Cummins ISB4.5 CM2150 Fault Code: 1117 PID: SID 251 SPN: 627 FMI: 2 Power Supply Lost With Ignition On – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The engine control module (ECM) receives constant voltage from the batteries through the unswitched battery wires that are connected directly to the positive (+) battery post. The ECM receives switched battery input through the vehicle keyswitch wire when the vehicle keyswitch is turned on.

Component Location
The ECM is connected to the battery by the OEM power harness through the ECM battery supply stub. This provides a constant power supply for the ECM. The location of the battery will vary with the original equipment manufacturer (OEM).

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault Codes
The ECM detects that primary ECM power supply dropped below a calibratible value while the keyswitch was in the ON position. The fault code will be active when the keyswitch is turned on, following the incomplete power-down event.

Action Taken When the Fault Code is Active
-The ECM records the fault code immediately when the diagnostic runs and fails.
-Power-down data like trip information, maintenance monitor, and fault information will not get saved to permanent memory when the keyswitch is turned OFF.
-Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code
To validate the repair, start the engine, let it idle for 1 minute, and shut it down properly. The ECM must see adequate primary ECM battery voltage when the keyswitch is turned OFF before the fault code will go inactive.

For engines equipped with SCR aftertreatment:
-This fault code can not be cleared with INSITE™ electronic service tool.
-The ECM will turn off the amber CHECK ENGINE lamp and/or MIL immediately after the diagnostic runs and passes.
-Use INSITE™ electronic service tool to verify the fault code is inactive.
-The inactive fault code will be cleared from the memory after 9600 hours of engine operation without a reoccurrence.

For all other engines:
-The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-For OBD engines, the ECM will turn off the MIL after 3 consecutive trips where the diagnostic runs and passes.
-The “Reset All Faults” command in the INSITE electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk
Make sure the ECM unswitched battery supply is coming directly from the battery and not the starter. If unswitched power is coming from the starter, it is possible for the battery voltage to drop low enough during cranking to set this fault active.

This fault can also be caused by resistance in the ECM battery supply (+) or (-) circuits. Resistance in these circuits can cause the voltage level at the ECM input to drop low enough to set Fault Code 1117 active.

Use of battery disconnect switches to turn off the engine or any device that disconnects battery voltage to the ECM within 10 seconds of turning the keyswitch off can cause damage to the aftertreatment system. The vehicle must not be operated with an active Fault Code 1117.