Cummins ISB4.5 CM2150 Fault Code: 238 PID: SID 232 SPN: 3511 FMI: 4 Sensor Supply 3 Circuit – Voltage Below Normal or Shorted to Low Source.

Circuit Description
The sensor supply 3 circuit provides a 5 volt supply to the primary engine speed/position sensor.

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 electronic control module (ECM) detects the sensor supply 3 signal voltage is less than a calibratible value for more than 1 second.

Action Taken When the Fault Code is Active
– The ECM illuminates the amber CHECK ENGINE light and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.
-The backup engine speed sensor will be used by the ECM for the engine speed signal.

Conditions for Clearing the Fault Code
-To validate the repair, start the engine and let it idle for 1 minute.
-The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
-The ECM will turn off the MIL after three consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and the MIL can also be cleared with INSITE™ electronic service tool.

Shop Talk
The ECM monitors the voltage level on the engine speed sensor 5-VDC supply circuit. If the voltage falls below a calibratible limit, this fault is recorded.

Possible Causes
– short circuit to ground in the engine harness, sensor, or ECM