SPN 635 - FMI 5 (Fault Code 394)

Engine Timing Actuator Driver Circuit - Current Below Normal or Open Circuit

Front Timing Actuator Circuit

Fault Code: 394
PID(P), SID(S): S20
SPN: 635
FMI: 5/5
Lamp: Amber

REASON: Low current or open circuit detected at front timing actuator circuit.

EFFECT: Possible reduced engine performance.

Circuit Description:
The timing actuators are actuated by the engine control module (ECM) to control fuel metering. Each timing actuator is connected to the ECM by a supply and a return wire. An electrical pulse is sent to the timing actuator from the ECM on the supply wire and returns to the ECM on the return wire. Each solenoid valve is normally closed, and it is only opened by an electrical pulse from the ECM during metering.

Component Location:
The front timing actuator is located on the fuel control housing.

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) has detected a low or open current at the front timing actuator circuit.

Action Taken When the Fault Code is Active:
• The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

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 amber CHECK 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:
-Signal circuit open or shorted to ground.
-Engine harness high resistance
• Loss of boost voltage inside the Engine Control Module (ECM).

Read More:
SPN 635 - FMI 6 (Fault Code 395)
SPN 1244 - FMI 5 (Fault Code 396)


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1 Response to "SPN 635 - FMI 5 (Fault Code 394)"

  1. ‌‌ ‌‌‌hello sir or madam
    Please ask me for Cummins ecm fault cod 635
    C sincerely yours