On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

DD: Fuel Rail Pressure (FRP) Sensor

DD1 DTC P0192: VERIFY DTC WITH FRP PID

Key on, engine off.
Verify there is sufficient fuel (NG only).
Access FRP PID.

Is the FRP PID voltage less than 0.2 volt?

Yes	No
KEY OFF. For NG vehicles: GO to DD2 . All others: Fault is present, GO to DD3 .	Fault is intermittent. GO to DD13 .

DD2 CHECK FUEL PRESSURE (NATURAL GAS)

Install fuel pressure gauge.
Key on engine running.
Obtain a pressure reading.

Is the fuel pressure reading greater than 345 kPa (50 psi)?

Yes	No
KEY OFF. GO to DD3 .	GO to Pinpoint Test HB1 .

DD3 GENERATE OPPOSITE SIGNAL

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect FRP harness connector.
Natural Gas Vehicles: Jumper FRP SIG pin to VREF pin at the FRP sensor harness connector.

Note: If any scan tool communication concern exists, remove jumper and go to DD24 .

Key on, engine off.
Access FRP V PID.

Is the FRP V PID voltage greater than 4.6 volts?

Yes	No
REPLACE FRP sensor (REFER to Electronic Engine Controls, Section 303-14 in the Workshop Manual).	GO to DD4

DD4 CHECK VREF VOLTAGE TO FRP SENSOR

Measure voltage between VREF and SIG RTN circuits at the FRP sensor harness connector.

Is the voltage between 4.0 and 6.0 volts?

Yes	No
KEY OFF. GO to DD5 .	GO to Pinpoint Test Step C1 .

DD5 CHECK FRP CIRCUIT FOR OPEN IN HARNESS

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of FRP circuit between PCM harness connector pin and FRP sensor harness connector.

Is the resistance less than 5.0 ohms?

Yes	No
GO to DD6 .	REPAIR open circuit.

DD6 CHECK FRP CIRCUIT FOR SHORTS TO SIG RTN AND PWR GND IN HARNESS

Measure resistance between FRP and SIG RTN circuits at the PCM harness connector.
Measure resistance of FRP circuit at the PCM harness connector and battery negative post.

Are both resistances greater than 10,000 ohms?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR short circuit.

DD7 DTC P0193: CHECK FUEL PRESSURE PID VALUE

Key on.
Access and monitor FRP V PID.

Is the FRP V PID voltage greater than 4.5 for NG and 4.8 for all others?

Yes	No
KEY OFF. For gasoline vehicles: GO to DD8 . For NG vehicles: GO to DD9 .	Fault is intermittent. GO to DD14 .

DD8 CHECK FUEL RAIL PRESSURE SENSOR FOR FUEL LEAKS

Remove vacuum hose from fuel rail pressure sensor.
Inspect sensor and hose for fuel.

Is fuel present?

Yes	No
REPLACE fuel rail pressure sensor.	GO to DD10 .

DD9 CHECK FUEL PRESSURE (NATURAL GAS)

Install fuel pressure gauge.
Key on, engine running.
Obtain a pressure reading.

Is the fuel pressure reading greater than 1034 kPa (150 psi)?

Yes	No
KEY OFF. GO to Pinpoint Test HB1 .	KEY OFF. GO to DD10 .

DD10 ATTEMPT TO INDUCE OPPOSITE FRP SIGNAL

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect FRP sensor.
Jumper FRP pin to SIG RTN pin at the FRP sensor harness connector.
Key on, engine off.
Access FRP V PID.

Note: If any scan tool communication concern exists, remove jumper and go to DD24 .

Is the FRP V PID voltage less than 0.2 volt?

Yes	No
KEY OFF. REPLACE fuel rail pressure (FRP) sensor (REFER to the Electronic Engine Controls, Section 303-14 in the Workshop Manual.)	KEY OFF. GO to DD12 .

DD11 DTC P0190: CHECK VREF TO FRP SENSOR

Note: Before proceeding to the following test step, a complete inspection of the fuel system for external leaks must be completed. Repair any leaks before continuing. Verify fuel level before beginning test steps.

Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FRP sensor harness connector.

Is the voltage between 4.0 and 6.0 volts?

Yes	No
KEY OFF. GO to DD13 .	KEY OFF. GO to DD12 .

DD12 CHECK FRP, SIG RTN AND VREF CIRCUITS FOR OPEN IN HARNESS

Disconnect PCM.
Measure resistance of FRP circuit between PCM pin and FRP sensor harness connector.
Measure resistance of SIG RTN circuit between PCM harness connector pin and FRP sensor harness connector.
Measure resistance of VREF circuit between PCM harness connector pin and FRP sensor harness connector.

Is each resistance less than 5.0 ohms?

Yes	No
GO to DD13 .	REPAIR open circuit.

DD13 CHECK FRP SENSOR RESISTANCE

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Measure resistance between FRP pin and VREF pin at the FRP sensor.
Measure resistance between FRP pin and SIG RTN pin at the sensor.

Note: For FRP sensor resistance specifications, refer to the Fuel Rail Pressure Sensor Test Information Chart in the beginning of this pinpoint test.

Is each resistance within normal range?

Yes	No
For continuous memory DTC P0190 only: GO to DD15 . For DTC P0192: REPLACE PCM (refer to Section 2 , Flash EEPROM). DTC P0193: GO to DD14 .	REPLACE FRP sensor.

DD14 CHECK FRP CIRCUIT FOR SHORT TO VREF AND VPWR IN HARNESS

Disconnect PCM.
Measure resistance between FRP and VPWR circuits at the PCM harness connector.
Measure resistance between FRP and VREF circuits at the PCM harness connector.

Are both resistances greater than 10,000 ohms?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR short circuit.

DD15 WIGGLE TEST THE FRP SENSOR CIRCUIT WHILE MONITORING FRP PID FOR SUDDEN VALUE CHANGE

Access FRP V PID.
While monitoring FRP V PID, tap on the FRP sensor; then wiggle the wiring while looking for sudden changes in the PID voltage as an indication of an intermittent fault.

Is a fault indicated?

Yes	No
REPAIR as necessary.	Unable to duplicate/identify fault at this time. GO to Pinpoint Test Step Z1 .

DD16 KOEO, KOER DTC P0191 AND CONTINUOUS DTCS P1168 P1169: CHECK FUEL PRESSURE

Key on.
Verify there is sufficient fuel (one eighth tank or greater).
Key off.
Fuel pressure gauge connected to Schrader valve.
Key on engine running.

Is the pressure reading within 138 kPa (20 psi) and 413 kPa (60 psi) for gasoline, or 552 kPa (80 psi) and 827 kPa (120 psi) for natural gas vehicles (NG)?

Yes	No
GO to DD17 .	REMOVE pressure gauge. GO to Pinpoint Test Step HC1 for gasoline or HB1 for NG vehicles.

DD17 CHECK FUEL PRESSURE WITH FRP PID

Connect scan tool.
Install fuel pressure gauge.
Key on.
Access and monitor FRP PID.

Is the FRP pressure reading within 10 psig of the fuel pressure gauge reading?

Yes	No
For DTCS P1168 or P1169: Complete PCM Reset to clear DTCS (REFER to Section 2 , Powertrain Control Module (PCM) Reset). DRIVE vehicle 3-5 minutes at a steady speed state. CHECK for Continuous Memory DTC P1168 or P1169. If P1168 or P1169 is displayed, GO to DD18 . All others: RERUN Quick Test.	For NG vehicle: GO to DD18 . All others: GO to DD19 .

DD18 VERIFY FUEL RAIL SOLENOID SHUT-OFF VALVE OPERATES

Key on.
Access and enter the Output Test Mode.
Cycle output ON and then OFF several times.

Is a click felt or heard from the fuel rail solenoid shut-off valve?

Yes	No
KEY OFF. EXIT Output Test Mode. RECONNECT solenoid valve. GO to DD19 .	KEY OFF. GO to DD22 .

DD19 CHECK VREF VOLTAGE TO FRP SENSOR

Disconnect FRP sensor.
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FRP sensor harness connector.

Is the voltage reading between 4.0 and 6.0 volts?

Yes	No
KEY OFF. GO to DD20 .	GO to Pinpoint Test Step C1 .

DD20 CHECK FRP CIRCUIT RESISTANCE

Note: Refer to the PCM connector pin numbers at the beginning of this pinpoint test.

Disconnect PCM.
Measure resistance of FRP circuit between PCM harness connector pin and the FRP sensor harness connector.
Measure resistance of SIG RTN circuit between PCM harness connector pin and FRP sensor harness connector.
Measure resistance of VREF circuit between PCM harness connector pin and FRP sensor harness connector.

Is each resistance less than 5.0 ohms?

Yes	No
GO to DD21 .	REPAIR as necessary.

DD21 MONITOR FRP V PID WITH SCAN TOOL

Key on, engine off.
Access FRP V PID.

Is the FRP V PID value less than 0.2 volt for NG, and greater than 4.8 volts for all others?

Yes	No
REPLACE FRP sensor.	REPLACE PCM (refer to Section 2 , Flash EEPROM).

DD22 CHECK VPWR VOLTAGE TO FUEL RAIL SOLENOID SHUT-OFF VALVE HARNESS CONNECTOR

Key on.
Access and enter Output Test Mode on the scan tool.
Select: ALL ON.
Disconnect the fuel rail solenoid shut-off valve at the harness connector.

Note: Measurement must be made within 7 seconds of activating test mode.

Measure voltage between the VPWR circuit at the fuel rail solenoid shut-off valve harness connector and battery negative post.

Is the voltage reading greater than 10.5 volts?

Yes	No
GO to DD23 .	KEY OFF. REPAIR open circuit.

DD23 CHECK GROUND CIRCUIT FOR OPEN IN HARNESS

Access and enter Output Test Mode on the scan tool.
Select: ALL ON.

Note: Measurement must be made within 7 seconds of activating test mode.

Measure voltage between the VPWR and ground circuits at the fuel rail solenoid shut-off valve harness connector.

Is the voltage reading greater than 10.5 volts?

Yes	No
KEY OFF. REPLACE fuel rail solenoid shut-off valve.	KEY OFF. REPAIR open circuit.

DD24 CHECK VREF VOLTAGE TO FRP SENSOR

Disconnect FRP sensor.
Key on, engine off.
Measure voltage between VREF and SIG RTN circuits at the FRP harness connector.

Is the voltage between 4.0 and 6.0 volts?

Yes	No
KEY OFF. GO to DD25 .	VREF is out of range. GO to Pinpoint Test Step C1 .

DD25 CHECK FOR FRP SIGNAL CIRCUIT SHORTED TO SIG RTN OR VREF PWR GND IN HARNESS

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Disconnect PCM.
Disconnect scan tool from DLC.
FRP disconnected.
Measure resistance between FRP and SIG RTN circuits at the PCM harness connector.
Measure resistance between FRP and VREF circuits at the PCM harness connector.
Measure resistance between FRP circuit at the PCM harness connector and battery negative post.

Is the resistance greater than 10,000 ohms?

Yes	No
REPLACE PCM (refer to Section 2 , Flash EEPROM).	REPAIR short.