PACCAR PX-9 CM2350 (2013-17) Fault Code:238 PID:SID 232 SPN:3511 FMI:4 Sensor Supply 3 Circuit – Voltage Below Normal or Shorted to Low Source

Reason:
Sensor Supply 3 Circuit – Voltage Below Normal or Shorted to Low Source. Low voltage detected on the +5 volt sensor supply circuit to the engine speed sensor.

Effect:
Engine may run rough, may stop running, may not start, or may be difficult to start.

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

Component Location:
Sensor Supply 3 originates in the engine wiring harness. It provides 5 VDC to the engine crankshaft 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 Engine Control Module (ECM) detected the sensor supply 3 signal voltage was out of range low.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) The backup engine speed sensor will be used by the ECM for the engine speed signal.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

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

Possible Causes:
1) Short circuit to ground in the engine harness, sensor, or ECM
2) Inactive fault codes
3) Damaged engine position sensor and circuit connected to the sensor supply and return
4) Faulty circuit response
5) Faulty crankshaft position sensor
6) Faulty ECM