SPN 1349 - FMI 4 (Fault Code 484)
Thursday, July 05, 2018
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SPN1349 FMI4
Injector Metering Rail 2 Pressure Sensor Circuit - Voltage Below Normal or Shorted to Low Source
CODES:
Fault Code: 484
PID(P), SID(S): P129
SPN: 1349
FMI: 4/4
Lamp: Amber
REASON: Low signal voltage detected at the fuel rail pressure sensor circuit.
EFFECT: Possible reduced engine performance.
Circuit Description:
The engine control module (ECM) provides a 5 volt supply to the fuel rail pressure sensor using a dedicated sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The fuel rail pressure sensor provides a primary fuel pressure signal to the ECM on the fuel rail pressure sensor signal 1 circuit. The sensor also provides a secondary fuel pressure sensor signal on the fuel rail pressure signal 2 circuit. This sensor signal voltage changes based on the pressure in the fuel rail. The ECM will detect a high signal voltage at high rail pressure conditions. The ECM will detect a low signal voltage during low rail pressure conditions.
Component Location:
The high-pressure fuel pump is mounted to the gear housing. The fuel pump actuator is mounted on the fuel pump. The fuel pressure sensor is mounted in the high pressure fuel rail. The fuel pressure relief valve is mounted on the high pressure fuel rail.
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 fuel rail pressure 2 signal voltage was less than 0.25-VDC for more than 3 seconds.
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:
• A malfunctioning fuel rail pressure sensor
• A short circuit to ground in the engine harness
Read More:
SPN 1349 - FMI 18 (Fault Code 486)
SPN 1349 - FMI 16 (Fault Code 485)
Blog.Teknisi
Injector Metering Rail 2 Pressure Sensor Circuit - Voltage Below Normal or Shorted to Low Source
 |
| Injector Metering Rail 2 Pressure Sensor Circuit |
CODES:
Fault Code: 484
PID(P), SID(S): P129
SPN: 1349
FMI: 4/4
Lamp: Amber
REASON: Low signal voltage detected at the fuel rail pressure sensor circuit.
EFFECT: Possible reduced engine performance.
Circuit Description:
The engine control module (ECM) provides a 5 volt supply to the fuel rail pressure sensor using a dedicated sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The fuel rail pressure sensor provides a primary fuel pressure signal to the ECM on the fuel rail pressure sensor signal 1 circuit. The sensor also provides a secondary fuel pressure sensor signal on the fuel rail pressure signal 2 circuit. This sensor signal voltage changes based on the pressure in the fuel rail. The ECM will detect a high signal voltage at high rail pressure conditions. The ECM will detect a low signal voltage during low rail pressure conditions.
Component Location:
The high-pressure fuel pump is mounted to the gear housing. The fuel pump actuator is mounted on the fuel pump. The fuel pressure sensor is mounted in the high pressure fuel rail. The fuel pressure relief valve is mounted on the high pressure fuel rail.
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 fuel rail pressure 2 signal voltage was less than 0.25-VDC for more than 3 seconds.
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:
• A malfunctioning fuel rail pressure sensor
• A short circuit to ground in the engine harness
Read More:
SPN 1349 - FMI 18 (Fault Code 486)
SPN 1349 - FMI 16 (Fault Code 485)
Blog.Teknisi
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