Diagnostic Aids

Perform this test when directed by QUICK TEST. This test is intended to diagnose the following:

• FRP Sensor
• Wiring Harness Circuits (FRP Signal & SIG RTN)
• Powertrain Control Module (PCM)

1. 1) KOEO & KOER DTC P0192: Verify DTC With FRP PID
   
   This DTC indicates FRP voltage fell below a minimum calibrated limit and a calibrated minimum amount of time during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
   • FRP Signal Shorted To SIG RTN Or PWR GND
   • FRP Signal Circuit Open (CNG Only)
   • Low Fuel Pressure (CNG Only)
   • Faulty FRP Sensor
   • Faulty PCM

   Ensure vehicle has fuel (CNG vehicles). Turn ignition switch to ON position. Using scan tool, access FRP PID from PID/DATA MONITOR & RECORD menu. If FRP PID voltage is less than .2 volt, go to next step for CNG vehicles or step  3) for all other vehicles. If FRP PID voltage is .2 volt or more, go to step  13).

2. 2) Check Fuel Pressure (CNG Vehicles)
   
   Turn ignition switch to OFF position. Install fuel pressure gauge. Start engine and observe fuel pressure. If fuel pressure is more than 50 psi (345 kPa), go to next step. If fuel pressure is 50 psi (345 kPa) or less, go to TEST HB, step 1) .
   NOTE: Fuel Rail Pressure (FRP) sensor may also be known as Injection Pressure (IP) sensor.
3. 3) Generate Opposite Signal
   
   Turn ignition switch to OFF position. Disconnect FRP sensor connector. On CNG vehicles, connect a jumper wire between FRP sensor harness connector FRP SIGNAL and VREF terminals. See Fig 1 or Fig 2 . On all other vehicles, if scan tool communication problem exists, disconnect jumper wire and go to step  24). Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. If FRP V PID voltage is more than 4.6 volts, replace FRP sensor. If FRP V PID voltage is 4.6 volts or less, disconnect jumper wire and go to next step.
4. 4) Check VREF Voltage To FRP Sensor
   
   Ensure FRP sensor is disconnected and ignition switch is turned to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN terminals. See Fig 1 or Fig 2 . If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and go to TEST C, step  1).
   Fig 1: Identifying Fuel Rail Pressure (FRP) Sensor Circuits & Connector Terminals (CNG Vehicles)

   Courtesy of FORD MOTOR CO.
   Fig 2: Identifying Fuel Rail Pressure (FRP) Sensor Circuits & Connector Terminals (All Other Models)

   Courtesy of FORD MOTOR CO.
5. 5) Check FRP Circuit For Open In Harness
   
   Turn ignition switch to OFF position. Leave FRP sensor disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance between of FRP circuit between FRP sensor harness connector terminal and PCM harness connector terminal. See Fig 1 or Fig 2 . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in FRP circuit.
6. 6) Check FRP Circuit For Short To PWR GND Or SIG RTN
   
   Using a DVOM, measure resistance between PCM harness connector FRP and SIG RTN terminals. See Fig 1 or Fig 2 . Using a DVOM, measure resistance of FRP circuit between negative battery terminal and PCM harness connector terminal. If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit.
7. 7) KOEO & KOER DTC P0193: Check FRP V PID Value
   
   This DTC indicates FRP voltage exceeded a maximum calibrated limit and a calibrated maximum amount of time during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
   • FRP Signal Shorted To VREF Or VPWR
   • FRP Signal Open (Gasoline Only)
   • High Fuel Pressure (Possible Faulty Fuel Pressure Regulator - CNG)
   • Faulty FRP Sensor
   • Faulty PCM

   Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. FRP V PID voltage should be more than 4.5 volts on CNG vehicles, and more than 4.8 volts on gasoline vehicles. If FRP V PID voltage is as specified, go to next step for gasoline vehicles and step  9) for CNG vehicles. If FRP V PID voltage is not as specified, fault may be intermittent. Go to step  14).

8. 8) Check FRP Sensor For Leaks
   
   Turn ignition switch to OFF position. Remove vacuum hose from FRP sensor. Inspect sensor and vacuum hose for fuel. If any fuel is present, replace FRP sensor. If no fuel is present, go to step  10).
9. 9) Check Fuel Pressure (CNG Vehicles)
   
   Turn ignition switch to OFF position. Install fuel pressure gauge. Start engine and observe fuel pressure. If fuel pressure is more than 150 psi (1034 kPa), go to TEST HB, step 1) . If fuel pressure is 150 psi (1034 kPa) or less, go to next step.
10. 10) Simulate Opposite FRP Signal To PCM
    
    Turn ignition switch to OFF position. Disconnect FRP sensor connector. Connect jumper wire between FRP sensor harness connector FRP and SIG RTN terminals. See Fig 1 or Fig 2 . Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. If scan tool communication problem is present, disconnect jumper wire and go to step  24). If FRP V PID voltage is less than .2 volt, replace FRP sensor. If FRP V PID voltage is .2 volt or more, go to step  12).
NOTE: Before performing this step, check for, and repair any fuel system external leaks and verify fuel level.
11. 11) KOEO & KOER DTC P0190: Check VREF Circuit To FRP Sensor
    DTC P0190 indicates FRP VREF voltage from PCM dropped below minimum calibrated voltage during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • VREF Open Circuit In Harness
    • VREF Open Circuit In Sensor
    • VREF Open Circuit In PCM

    Disconnect FRP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN terminals. See Fig 1 or Fig 2 . If voltage is 4-6 volts, go to step  13). If voltage is not 4-6 volts, go to next step.

12. 12) Check FRP, SIG RTN & VREF Circuits For Opens
    
    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of FRP, SIG RTN and VREF circuits between appropriate FRP sensor harness connector terminal and PCM harness connector terminal. See Fig 1 or Fig 2 . If all resistance measurements are less than 5 ohms, go to next step. If any resistance measurement is 5 ohms or more, repair open in affected FRP, SIG RTN or VREF circuit.
13. 13) Check FRP Sensor Resistance
    
    Using a DVOM, measure resistance between FRP sensor FRP and SIG RTN terminals. See Fig 1 or Fig 2 . Using a DVOM, measure resistance between FRP sensor FRP and VREF terminals. FRP sensor resistance should be 30-40 k/ohms. If either resistance measurement is not within specification, replace FRP sensor. If both resistance measurements are within specification, proceed as follows:
    • If only Continuous Memory DTC P0190 is present, go to step  15).
    • If DTC P0192 is present, replace PCM.
    • If DTC P0193 is present, go to next step.
14. 14) Check FRP Circuit For Short To VREF Or VPWR
    
    Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure between PCM harness connector FRP and VREF terminals. See Fig 1 or Fig 2 . Using a DVOM, measure resistance between PCM harness connector FRP and VPWR terminals. See PCM VPWR TERMINAL IDENTIFICATION  table. If both resistance measurements are more than 10 k/ohms, replace PCM. If either resistance measurement is 10 k/ohms or less, repair short in affected circuit.
    PCM VPWR TERMINAL IDENTIFICATION
    
    

    Application	PCM Terminal No.
    Cougar	71 & 97
    LS	A32 & A33
    All Other Models	71

15. 15) Continuous Memory DTC P0190, P0192 & P0193: Check For Intermittent Fault
    
    Reconnect FRP sensor connector. Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. Observe FRP V PID voltage reading for fault while tapping on FRP sensor. Wiggle and bend wiring harness and connector between sensor and PCM. Fault will be indicated by a sudden change in PID voltage. If fault is indicated, isolate and repair as necessary. If fault is not indicated, symptom is intermittent and cannot be located at this time. Go to TEST Z, step 1) for additional test procedures.
NOTE: On CNG models, if vehicle is a no-start, go to TEST HB, step 1) .
16. 16) KOEO, KOER & Continuous Memory DTC P0191, Or Continuous Memory P1168 Or P1169 (CNG Only): Check Fuel Pressure
    DTC P0191, P1168 or P1169 indicate fuel pressure fell below minimum or exceeded maximum calibrated limit for a calibrated period of time during Comprehensive Component Monitor (CCM). Possible causes for this fault are:
    • High Fuel Pressure
    • Low Fuel Pressure
    • Excessive Resistance In Circuit
    • Faulty FRP Sensor
    • Low Or No Fuel

    Turn ignition switch to ON position. Ensure vehicle has at least 1/8 tank of fuel. Turn ignition switch to OFF position. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE procedure under FUEL SYSTEM in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Connect pressure gauge to Schrader valve on fuel rail. With engine running, check fuel pressure. Fuel pressure should be within specification. See FUEL PRESSURE SPECIFICATIONS . If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to TEST HB, step 1) for CNG vehicles, or TEST HC, step 1) for gasoline vehicles.

17. 17) Check Fuel Pressure With FRP PID
    
    Connect scan tool to Data Link Connector (DLC). Ensure fuel pressure gauge is still connected. Turn ignition switch to ON position. Using scan tool, select FRP PID from PID/DATA MONITOR & RECORD menu. If FRP PID value is not within 10 psi of fuel pressure gauge measurement, go to next step for CNG vehicles, or step  19) for all other vehicles. If FRP PID value is within 10 psi of fuel pressure gauge measurement, proceed as follows:
    • If DTC P1168 or DTC P1169 are present, clear DTCs. See CLEARING CODES under SELF-DIAGNOSTIC SYSTEM. Road test vehicle 3-5 minutes at a steady speed. Stop vehicle and check for Continuous Memory DTCs. If DTC P1168 or DTC P1169 are still present, go to next step.
    • If any other DTC is present, repeat QUICK TEST .
    • If DTC P0191 is present in Continuous Memory, go to step  15).
18. 18) Check Fuel Rail Solenoid Operation
    
    Turn ignition switch to ON position. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE under ADDITIONAL SYSTEM FUNCTIONS. While observing fuel rail solenoid, cycle output ON and OFF several times. If solenoid clicking can be heard or felt, turn ignition switch to OFF position, exit OUTPUT TEST MODE and go to next step. If no solenoid clicking can be heard or felt, turn ignition switch to OFF position and go to step  22).
19. 19) Check VREF Voltage To FRP Sensor
    
    Disconnect FRP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN terminals. See Fig 1 or Fig 2 . If voltage is 4-6 volts, turn ignition switch to OFF position and go to next step. If voltage is not 4-6 volts, go to TEST C, step  1).
20. 20) Check FRP Circuit For Excessive Resistance
    
    Ensure ignition switch is turned to OFF position. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of FRP, SIG RTN and VREF circuits between appropriate FRP sensor harness connector terminal and PCM harness connector terminal. See Fig 1 or Fig 2 . If all resistance measurements are less than 5 ohms, go to next step. If any resistance measurement is 5 ohms or more, repair open in affected FRP, SIG RTN or VREF circuit.
21. 21) Monitor FRP V PID With Scan Tool
    
    Turn ignition switch to ON position. Using scan tool, select FRP V PID from PID/DATA MONITOR & RECORD menu. If FRP V PID voltage is less than .2 volt on CNG vehicles, or more than 4.8 volts on all other vehicles, replace FRP sensor. If FRP V PID voltage is not as specified, replace PCM.
NOTE: When ALL ON is selected in OUTPUT TEST MODE, voltage measurement must be made within 7 seconds of activating test mode.
22. 22) Check FSV VPWR To Fuel Rail Solenoid
    Disconnect fuel rail solenoid connector. Turn ignition switch to ON position. Using scan tool, access OUTPUT TEST MODE. See OUTPUT TEST MODE under ADDITIONAL SYSTEM FUNCTIONS. Select outputs ALL ON. Using a DVOM, measure voltage between negative battery terminal and fuel rail solenoid harness connector FSV VPWR terminal (Pink/Black wire). See WIRING DIAGRAMS article. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in FSV VPWR circuit.
23. 23) Check Ground Circuit For Open
    
    Using a DVOM, measure resistance between negative battery terminal and fuel rail solenoid harness connector ground terminal (Black wire). If resistance is less than 5 ohms, replace fuel rail solenoid. If resistance is 5 ohms or more, repair open in ground circuit.
24. 24) Check VREF Voltage To FRP Sensor
    
    Disconnect FRP sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between FRP sensor harness connector VREF and SIG RTN circuit terminals. If voltage is 4-6 volts, turn ignition switch to OFF position and go to next step. If voltage is not 4-6 volts, VREF is out of range. Go to TEST C, step  1).
25. 25) Check For Shorted FRP Signal
    
    Disconnect scan tool from Data Link Connector (DLC). Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance between PCM harness connector FRP and SIG RTN terminals, between PCM harness connector FRP and VREF terminals, and between PCM harness connector FRP terminal and battery negative terminal. See WIRING DIAGRAMS article. If all resistance measurements are more than 10 k/ohms, replace PCM. If any resistance measurement is 10 k/ohms or less, repair short in affected circuit.