Power Lost Without Ignition Off – Data Erratic, Intermittent, or Incorrect
|Fault Code: 1117
Power Lost Without Ignition Off – Data Erratic, Intermittent, or Incorrect. Supply voltage to the ECM fell below 6.2-VDC momentarily, or the ECM was not allowed to power down correctly (retain battery voltage for 30 seconds after key OFF).
Possible no noticeable performance effects or engine dying or hard starting. Fault information, trip information, and maintenance monitor data can be inaccurate.
Unswitched Battery Supply
The 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.
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 OEM. Refer to the OEM service manual.
This fault is set active if the ECM battery supply voltage drops below + 6.2-VDC while the keyswitch is in the ON position.
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.
Where the fault code is inactive, familiarize yourself with the vehicle shut down practices used by the operator. For example, if there are controls inside the cab that can interrupt the (ECM) power supply (before the end of the 30 second power down process after key OFF), these should be considered as a potential cause when the fault code is being addressed. This should be explained to the operator.
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.
This fault can also be caused by a short to ground in the injector wiring harness. Check to be sure the injector wires are oriented so that they will not interfere with a rocker lever or other components in the overhead system. Keep in mind that certain operating conditions can cause the rocker levers to operate outside their normal range of motion.
This fault code can also be caused by noise transmitted over the J1587 or J1939 data links. The transmitted noise can cause a momentary interruption in the ECM power, which causes Fault Code 1117 to log. During troubleshooting, isolate the engine from the chassis to determine if any of the data links are conducting noise to the engine.