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SPN 632 - FMI 4 (Fault Code 254)

SPN632 FMI4
Engine Fuel Shutoff Valve Driver Circuit - Voltage Below Normal or Shorted to Low Source

Fuel Shutoff Valve Circuit


CODES:
Fault Code: 254
PID(P), SID(S): S17
SPN: 632
FMI: 4/4
Lamp: Red

REASON: Engine Fuel Shutoff Valve Driver Circuit - Voltage Below Normal or Shorted to Low Source. Low voltage detected at fuel shutoff valve circuit.

EFFECT: Engine will shut down.

Circuit Description:
The fuel shutoff valve is a device used by the engine control module (ECM) to control the engine fuel supply. When the ECM energizes the engine fuel shutoff valve driver circuit, the engine fuel shutoff valve is opened. Zero voltage to the engine fuel shutoff valve will close the engine fuel shutoff valve.

Component Location:
The fuel shutoff valve is located near the fuel pump.

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 fuel shutoff valve circuit PWM signal is not detected to be system voltage when the PWM signal is turned on.

Action Taken When the Fault Code is Active:
• The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
-The engine fuel shutoff valve will not open. The engine will not start or run

Conditions for Clearing the Fault Code:
• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
• The "Reset All Faults" command in the recommended Cummins® electronic service tool or equivalent can be used to clear active and inactive faults.

Shop Talk:
Possible causes of this fault code include:
-Short circuit to ground in the engine harness, connectors, or fuel shutoff valve.

-Inspect the fuel shutoff supply circuit for external wires that can be spliced in to power another device. Remove any extra wires that are found in the circuit. If there is an external shutdown system on the vehicle that uses the fuel shutoff valve for engine shutdown, make sure it has not malfunctioned and pulled down the voltage on the fuel shutoff circuit. Inspect the engine-to-chassis ground wire to make sure it is securely fastened to a clean, dry, conductive surface.


Read More:
SPN 171 - FMI 4 (Fault Code 256)
SPN 632 - FMI 3 (Fault Code 255)








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