Cummins ISB4.5 CM2150 Fault Code: 441 PID: 168 SPN: 168 FMI: 1 Battery 1 Voltage – Data Valid but Below Normal Operating Range – Moderately Severe Level.

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. There is one 30-ampere fuse in the unswitched battery wires to protect the original equipment manufacturer (OEM) harness. The ECM receives switched battery input through the vehicle keyswitch wire when the vehicle keyswitch is turned ON. The battery return wires are connected directly to the negative (-) battery post.

Component Location
The ECM is connected to the battery by the OEM harness. This direct link provides a constant power supply for the ECM. The location of the battery will vary with the OEM. Refer to the OEM troubleshooting and repair manual for the battery location.

Not applicable.

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

Conditions for Setting the Fault Codes
The ECM detects that the main battery supply voltage is less than 6-VDC.

Action Taken When the Fault Code is Active
-The ECM logs the fault code and illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
-The ECM will turn off the fault code and amber CHECK ENGINE light, and the fault code will go inactive immediately after the battery voltage is above 6-VDC
-This fault code can also be cleared with INSITE™ electronic service tool.

Shop Talk
This fault code is logged when the ECM battery supply voltage drops below 6-VDC.

-Verify that the ECM unswitched power supply is coming from the batteries and not the starter or other device. Check for possible weak batteries.
-If the ECM unswitched battery supply is taken from the starter, check for low voltage during cranking. Low voltage during cranking can cause the ECM power supply to drop below specifications and log Fault Code 441.