Page 527 of 5267

When Monitored:
At key on.
Set Condition:
The fuel pressure sensor reading at key on does not match the expected fuel pressure reading at key on.
Possible Causes
OTHER DTC’S PRESENT
FUEL RAIL PRESSURE SENSOR
FUEL SYSTEM TAMPERING
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.OTHER DTC’S PRESENT
With the scan tool, read DTCs.
Are any DTC’s present?
Ye s>>
Repair other DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.FUEL PRESSURE READING
Using the scan tool, monitor the actual fuel pressure reading while the keyis on and engine is not running.
Is the actual fuel pressure reading greater than 870 psi?
Ye s>>
Go To 3
No>>
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
3.FUEL RAIL PRESSURE SENSOR
Visually inspect the fuel system components for signs of tampering, pay particular attention to the fuel pressure
sensor on the fuel rail and the fuel pressure sensor wiring harness.
Were any signs of tampering discovered?
No>>
Replace the Fuel rail pressure sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Ye s>>
Restore Fuel system to original condition.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 528 of 5267
P0192-FUEL PRESSURE SENSOR VOLTAGE TOO LOW
For a complete wiring diagramRefer to Section 8W.
Page 529 of 5267

When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.
Set Condition:
The circuit voltage to the ECM falls below a calibrated threshold for a certain period of time.
Possible Causes
OTHER DTC’S
FUEL PRESSURE SENSOR
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO (F855) RETURN CIRCUIT
(K181) SIGNAL CIRCUIT SHORTED TO (F855) RETURN CIRCUIT
(K181) SIGNAL CIRCUIT OPEN
(F855) 5-VOLT SUPPLY CIRCUIT OPEN
(K181) SIGNAL CIRCUIT SHORTED TO GROUND
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.OTHER DTC’S
Ignition on, engine not running.
With the scan tool, read DTCs.
Do you have multiple DTC’s?
Ye s>>
Repair other DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.(F855) 5-VOLT SUPPLY AND (K915) RETURN CIRCUIT
Turn the ignition off.
Disconnect the Fuel Pressure sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
Measure the voltage between the (F855) 5-volt supply and (K915)
return circuits of the Fuel pressure sensor harness connector.
Is the voltage between 4.5 and 5.5 volts?
Ye s>>
Go To 3
No>>
Go To 4
Page 530 of 5267

3.FUEL PRESSURE SENSOR
Reconnect the disconnected Fuel Pressure Sensor harness connector.
While monitoring scan tool, disconnect the Fuel Pressure sensor harness connector.
Does the DTC P0193 set?
Ye s>>
Replace the Fuel Pressure Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 4
4.(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO (K915) RETURN CIRCUIT
Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the Fuel Pressure sensor harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance between the (F855) 5-volt supply circuit and
(K915) return circuit in the sensor harness connector.
Is the resistance greater than 100 K Ohms?
Ye s>>
Go To 5
No>>
Repair the shorted circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
5.(K181) SIGNAL CIRCUIT SHORTED TO (K915) RETURN CIRCUIT
Measure the resistance between the (K181) signal circuit and (K915)
return circuit in the sensor connector.
Is the resistance greater than 100 K Ohms?
Ye s>>
Go To 6
No>>
Repair the shorted circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 531 of 5267
6.(K181) SIGNAL CIRCUIT OPEN
Measure the resistance between the signal (K181) circuit in the sensor
harness connector with the (K181) signal circuit in the ECM harness
connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 7
No>>
Repair the open (K181) signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
7.(F855) 5-VOLT SUPPLY CIRCUIT OPEN
Measure the resistance between the supply (F855) circuit in the sensor
harness connector with the (F855) 5-volt supply circuit in the ECM har-
ness connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 8
No>>
Repair the open (F855) 5-volt supply circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 532 of 5267

8.(K181) SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between the (K181) signal circuit in the sensor
harness connector and battery negative.
Is the resistance greater than 100 K Ohms?
Ye s>>
Go To 9
No>>
Repair (K181) signal circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
9.(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
Measure the resistance between the (F855) 5-volt supply circuit in the
sensor harness connector and battery negative.
Is the resistance greater than 100 K Ohms?
Ye s>>
Go To 10
No>>
Repair (F855) 5-volt Supply circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
10.ECM
Reconnect the disconnected Fuel pressure sensor harness connector and ECM harness connectors.
While monitoring scan tool, disconnect the Fuel Pressure sensor connector.
Does the DTC P0193 set?
Ye s>>
Te s t C o m p l e t e .
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 533 of 5267
P0193-FUEL PRESSURE SENSOR VOLTAGE TOO HIGH
For a complete wiring diagramRefer to Section 8W.
Page 534 of 5267

When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.
Set Condition:
The circuit voltage to the ECM is above a calibrated threshold for a certainperiod of time.
Possible Causes
OTHER DTC’S
FUEL PRESSURE SENSOR
(K181) SIGNAL CIRCUIT SHORTED TO VOLTAGE
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
(K181) SIGNAL CIRCUIT SHORTED TO (F855) 5-VOLT SUPPLY CIRCUIT
(K915) RETURN CIRCUIT OPEN
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.OTHER DTC’S
Ignition on, engine not running.
With the scan tool, read DTCs.
Do you have multiple DTC’s?
Ye s>>
Refer to multiple fault troubleshooting tree.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.(F855) 5-VOLT SUPPLY AND (K915) RETURN CIRCUIT
Turn the ignition off.
Disconnect the Fuel Pressure sensor harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
Measure the voltage between the (F855) 5-volt supply and (K915)
return circuits of the Fuel pressure sensor harness connector.
Is the voltage between 4.5 and 5.5 volts?
Ye s>>
Go To 3
No>>
Go To 4