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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 2812 (Engine Controls Self-Diagnostics - EEC-V - CNG & Gasoline - System Tests A - FD) >> Test De: Flex Fuel Sensor >> Diagnostic Aids

Diagnostic Aids

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NOTE: After each service or repair procedure has been completed, reconnect all components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-V systems are working properly and DTCs are no longer present.
NOTE: Some Flex-Fuel Vehicles (FFV) DO NOT use an FF sensor. If FFV is not equipped with an FF sensor, PCM is used to determine fuel alcohol percentage by compiling input signals from specific EEC sensors.

Perform this test only when directed by QUICK TEST. This system test is intended to diagnose the following components and circuits:

NOTE: Type of fuel vehicle uses can be identified by checking calibration sticker on left door jam. See FUEL TYPE IDENTIFICATION  table. Fuel type can also be identified by checking label on fuel filler door.
FUEL TYPE IDENTIFICATION (1)

Calibration Fuel Type
610C Ethanol
610G Methanol
(1) Calibration sticker is located on left door jam. Fuel type is also identified on fuel filler door.
NOTE: Proceed to DTC testing steps listed in FAULT CODE SETTING CONDITION  table of fault code setting condition.
FAULT CODE SETTING CONDITION

Fault Code KOEO KOER Continuous Memory
P0176    DE1  DE20

  1. 1) KOER DTC P0176: Check VPWR Voltage To FF Sensor

    DTC P0176 is set when FF sensor signal falls out of minimum or exceeds maximum calibrated range. Possible causes for this fault are:
    • Open Or Short In FF Sensor VPRW Circuit
    • Open In Battery Ground To FF Sensor Circuit
    • Open In FF Sensor Signal Circuit
    • Short To Ground In FF Sensor Signal Circuit
    • Short To VPWR In FF Sensor Battery Ground Circuit
    • Short To VPWR In FF Sensor Signal Circuit
    • Fuel Separation Or Contamination
    • Faulty FF Sensor
    • Faulty Powertrain Control Module (PCM)

    Turn ignition switch to OFF position. Disconnect FF sensor connector. Turn ignition switch to ON position. Using a DVOM, measure voltage of VPWR circuit between FF sensor harness connector terminal and negative battery terminal. See Fig 1. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in VPWR circuit. Check condition of related fuses or fuse links. If fuses or fuse links are okay, locate and repair open in VPWR circuit. If fuses or fuse links are faulty, check VPWR circuit for short to ground. Repair as necessary.

    Fig 1: Identifying Flex Fuel Sensor Circuits & Connector Terminals
    G99H02088Courtesy of FORD MOTOR CO.

  2. 2) Check Battery Ground Circuit For Open

    Turn ignition switch to OFF position. Using a DVOM, measure resistance of BATT GND circuit between FF sensor harness connector terminal and negative battery terminal. See Fig 1. If resistance is more than 10 k/ohms, repair open in BATT GND circuit. If resistance is 10 k/ohms or less, go to next step.

  3. 3) Check FFS SIG Circuit For Open

    Ensure ignition switch is turned to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of FFS SIG circuit between FF sensor harness connector terminal and PCM harness connector terminal. See Fig 1. If resistance is 5 ohms or more, repair open in FFS SIG circuit. If resistance is less than 5 ohms, go to next step.

  4. 4) Check FFS SIG Circuit For Short To Power

    Disconnect scan tool from Data Link Connector (DLC). Using a DVOM, measure resistance between PCM harness connector terminals No. 34 (FFS SIG) and No. 71 (VPWR). See Fig 1. If resistance is 10 k/ohms or less, repair short between FFS SIG and VPWR circuits. If resistance is more than 10 k/ohms, go to next step.

  5. 5) Check FFS SIG Circuit For Short To Ground

    Using a DVOM, measure resistance between PCM harness connector terminal No. 34 (FFS SIG) and PWR GND terminals. See Fig 1. See PCM PWR GND, SIG RTN & VREF TERMINAL IDENTIFICATION . If any resistance measurement is 10 k/ohms or less, repair short to ground in affected circuit. If all resistance measurements are more than 10 k/ohms, go to next step.

  6. 6) Check FF Sensor Dedicated Failure Mode PID

    Reconnect all components. Connect scan tool to DLC. Start engine and allow to idle. Using scan tool, select FFFM PID from PID/DATA MONITOR & RECORD menu. If FFFM PID value indicates ON condition, go to next step and check FF sensor. If FFFM PID value does not indicate ON condition, proceed as follows:
    • On ethanol vehicles, if percentage of ethanol in fuel is known, go to step  10).
    • On methanol vehicles, if percentage of methanol in fuel is known, go to step  11).
    • If percentage of ethanol or methanol in fuel is not known, go to step  8).

  7. 7) Check FF Sensor Frequency

    Leave engine idling. Using scan tool, select FF PID from PID/DATA MONITOR & RECORD menu. If FF PID value does not indicate 40-160 Hz, turn ignition switch to OFF position and go to step  12). If FF PID value indicates 40-160 Hz, FF sensor output does not indicate a failure. Turn ignition switch to OFF position and proceed as follows:
    • On ethanol vehicles, if percentage of ethanol in fuel is known, go to step  10).
    • On methanol vehicles, if percentage of methanol in fuel is known, go to step  11).
    • If percentage of ethanol or methanol in fuel is not known, go to next step.

  8. 8) Determine Water Ethanol/Methanol & Gasoline Separation Point

    Rotunda FFV Fuel Test Kit (014-00770), is required for this test. Ensure ignition switch is turned to OFF position. Ensure FF sensor is disconnected. Place hose end of fuel drain hose assembly in clean gas can. Connect fuel drain hose to fuel pressure relief valve. Fill beaker with 5 ml of clean water. Turn connector clockwise to tighten. Turn ON/OFF valve clockwise to open. Turn ignition switch to ON position and leave on until at least 22 ml of fuel is pumped into gas can.

    Pour 20 ml of fuel into 25 ml graduated cylinder. Pour enough water into 25 ml graduated cylinder to bring total volume to 24 ml. Plug graduated cylinder and shake graduated cylinder to mix water and fuel. Let graduated cylinder stand for 3 minutes, allowing fluids to separate. Water and methanol (or ethanol and water) will blend and settle on bottom of graduated cylinder. Gasoline will rise to top of graduated cylinder. Record level on graduated cylinder where methanol and water (or ethanol and water) mixture and gasoline meet. Go to next step.

  9. 9) Determine Ethanol/Methanol Percentage

    To determine the percentage of ethanol or methanol in fuel, use the following equation: Percent Of Methanol (Or Ethanol) = (A - 4) x 5  . Specification "A" equals level on graduated cylinder recorded from step  8) where methanol/water (or ethanol/water) mixture and gasoline meet. See Fig 2. Example, if measurement from step  8) is 14 ml, percentage of methanol (or ethanol) in fuel mixture is (14 - 4) x 5, which equals 50. Therefore, percentage of methanol (or ethanol) in fuel mixture is 50 percent. Determine percentage of ethanol or methanol in fuel before continuing. The accuracy of this equation is plus or minus 10 percent. Dispose of fuel properly. Go to step  11) for methanol powered vehicles or go to next step for ethanol powered vehicles.
    Fig 2: Testing Flex Fuel Sample
    G95E35943Courtesy of FORD MOTOR CO.

  10. 10) Check FF Sensor Operation (Ethanol Vehicles)

    Start engine and allow to idle. Using scan tool, select FF PID from PID/DATA MONITOR & RECORD menu. Record FF PID frequency reading. Use FF PID frequency reading to determine corresponding frequency range for known percentage of ethanol. See FF PID ETHANOL RATING  table. If FF PID frequency reading falls within frequency range, replace PCM. If FF PID frequency reading does not fall within the frequency range, check fuel for contamination. If fuel is not contaminated, replace FF sensor. If fuel is contaminated, drain and refill fuel tank. Start engine and allow to idle until old fuel is purged from fuel rails. Repeat this step. If FF PID frequency reading still does not fall within the frequency range, replace FF sensor.
    FF PID ETHANOL RATING (1)

    Ethanol Blend % FF PID Frequency - Hz
    Zero 40-60
    15 50-70
    25 60-80
    35 65-85
    45 75-100
    55 80-105
    65 90-110
    75 95-120
    85 105-125
    (1) Ratings may vary between listed values.

  11. 11) Check FF Sensor Operation (Methanol Vehicles)

    Start engine and allow to idle. Using scan tool, select FF PID from PID/DATA MONITOR & RECORD menu. Record FF PID frequency reading. Use FF PID frequency reading to determine corresponding frequency range for known percentage of methanol. See FF PID METHANOL RATING  table. If FF PID frequency reading falls within the frequency range, replace PCM. If FF PID frequency reading does not fall within the frequency range, check fuel for contamination. If fuel is not contaminated, replace FF sensor. If fuel is contaminated, drain and refill fuel tank. Start engine and allow to idle until old fuel is purged from fuel rails. Repeat this step. If FF PID frequency reading still does not fall within the frequency range, replace FF sensor.
    FF PID METHANOL RATING (1)

    Methanol Blend % FF PID Frequency - Hz
    Zero 40-60
    15 55-75
    25 65-85
    35 75-95
    45 85-105
    55 95-115
    65 105-125
    75 115-135
    85 125-145
    (1) Ratings may vary between listed values.

  12. 12) Check PCM Function

    Disconnect FF sensor. Using scan tool, select FF PID from PID/DATA MONITOR & RECORD menu. Using NGS scan tool signal simulator or equivalent, feed a 100Hz signal into FF sensor harness connector FFS SIG circuit terminal. See Fig 1. Turn ignition switch to ON position. If FF PID frequency reading reflects frequency input signal, turn ignition switch to OFF position and replace FF sensor. If FF PID frequency reading does not reflect frequency input signal, turn ignition switch to OFF position and replace PCM.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 12) to step 20). No test procedures have been omitted.

  13. 20) Continuous DTC P0176

    Continuous DTC P0176 is set when FF sensor signal falls out of a minimum or exceeds a maximum calibrated range. Possible causes for this fault are:
    • Open Or Short In FF Sensor VPRW Circuit
    • Open In Battery Ground To FF Sensor Circuit
    • Open In FF Sensor Signal Circuit
    • Short To Ground In FF Sensor Signal Circuit
    • Short To VPWR In FF Sensor Battery Ground Circuit
    • Short To VPWR In FF Sensor Signal Circuit
    • Fuel Separation Or Contamination
    • Faulty FF Sensor
    • Faulty Powertrain Control Module (PCM)

    Perform KOER ON-DEMAND SELF-TEST . Ignore all other DTCs at this time. If KOER DTC P0176 is present, hard fault is present. Go to step  1). If KOER DTC P0176 is not present, check for intermittent fault. Go to TEST Z, step 1) .

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