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Test JB: Secondary Ignition: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) For KOER & Continuous Memory Only DTC P0350: Preliminary Test
    DTC P0350 is set when PCM does not receive a valid Ignition Driver Module (IDM) pulse signal from ignition module integrated in PCM. Possible causes are:
    • IGN START/RUN circuit open or shorted.
    • Coil driver circuit open, or shorted to GND or VPWR.
    • Faulty coil.
    • Faulty Powertrain Control Module (PCM).

    Ensure battery is fully charged and all accessories are off. Check all wiring harnesses and connectors for damage, burned or overheated insulation. Ensure all coils and plug wires are securely connected. Repair as necessary and perform DRIVE CYCLES . Ensure OBD-II DRIVE CYCLES is performed to verify repair. If no concerns are found, proceed as follows:

    • For coil pack applications using engine analyzer, go to next step.
    • For coil pack applications not using engine analyzer, go to step  20).
    • For coil on plug applications, go to step  15).

    2. NOTE: For diagnostic procedures to provide accurate results, calibration of engine analyzer must be maintained. Refer to equipment manufacturer's manual for proper procedure to calibrate engine analyzer. If equipment manual is not available, an estimate of calibration can be made by connecting Spark Tester (D81P-6666-A), to a properly operating ignition system and measuring firing voltage of spark tester only. Spark tester firing voltage should be approximately 12 kilovolts.

  2. 2) Connect Engine Analyzer
    Install engine analyzer to diagnose concerns with secondary side of ignition system and go to next step.

  3. 3) Check For Ignition Pattern

    Crank engine and observe scope pattern. If scope pattern is not flat, go to next step. If scope pattern is flat (no spark on all cylinders), turn ignition switch to OFF position and go to TEST B, step 5) (LS and Thunderbird), or check IGN START/RUN circuit (all others). Check all related fuses and fuse links. If fuse or fuse link is blown, check IGN START/RUN circuit for short to GND. Repair as necessary and perform DRIVE CYCLES . Ensure OBD-II DRIVE CYCLES is performed to verify repair.
    4. NOTE: Spark plugs are fired up to 4 strikes per ignition cycle. Multi-strike operating mode is dependent on PCM calibration and is operational only with engine speed at less than 2000 RPM. With engine speed at more than 2000 RPM, spark plugs are fired once per ignition cycle.
    Fig 1: Identifying Normal Spark Pattern
    G00077829Courtesy of FORD MOTOR CO.

  4. 4) Check For Normal Ignition Pattern
    Start engine and allow to idle. If engine does not start, crank engine. Observe scope pattern and check average spark output voltage and variation of pattern. See Fig 1. If spark patterns are not even and average spark plug firing voltage is not 9-15 kilovolts, go to next step. If concern is intermittent and spark pattern is even and average value of spark plug firing voltage is 9-15 kilovolts, fault is unable to be duplicated at this time. Go to TEST Z, step 1) . If average spark plug firing voltage is 9-15 kilovolts, ignition system is functioning properly. If directed here from SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article, return to symptom test that directed you here. If directed here from TEST HD, step  3), return to TEST HD, step  4). If directed here from TEST A, step 6) , return to TEST A, step 6) .

  5. 5) Check For 2 Missing Spark Patterns On Same Coil

    Observe scope pattern and check for 2 missing spark patterns from same coil. See Fig 2. If spark is not missing from 2 cylinders on same coil, go to next step. If spark is missing from 2 cylinders on same coil, check spark plug wires and spark plugs on missing cylinders. Measure resistance of spark plug wires. Spark plug wire resistance should be 7 k/ohms or less per foot. Measure resistance of spark plugs. Spark plug resistance should be 2-20 k/ohms. Repair as necessary and retest. If spark plug wires and spark plugs are okay, go to TEST JE, step 1) .
    Fig 2: Identifying 2 Missing Spark Patterns On Same Coil
    G00077830Courtesy of FORD MOTOR CO.

  6. 6) Check For Missing Spark Pattern

    Observe scope pattern and check for missing spark pattern. See Fig 3. If spark is present from all cylinders, go to next step. If spark is missing from one cylinder, check spark plug wire and spark plug where missing cylinder pattern exists. Measure resistance of spark plug wire. Spark plug wire resistance should be 7 k/ohms or less per foot. Measure resistance of spark plug. Spark plug resistance should be 2-20 k/ohms. Repair as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair.
    Fig 3: Identifying One Missing Spark Pattern
    G00077831Courtesy of FORD MOTOR CO.

  7. 7) Check For High Spark Plug Firing Voltage

    Observe scope pattern and check for high spark firing voltage and pattern. See Fig 4. If spark plug firing voltage is 15 kilovolts or less, go to next step. If average spark plug firing voltage is more than 15 kilovolts, check spark plug wires and spark plugs on affected cylinders. Measure resistance of spark plug wires. Spark plug wire resistance should be 7 k/ohms or less per foot. Measure resistance of spark plugs. Spark plug resistance should be 2-20 k/ohms. Repair as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair.
    Fig 4: Identifying High Spark Plug Firing Voltage
    G00088375Courtesy of FORD MOTOR CO.

  8. 8) Check For Low Spark Plug Firing Voltage

    Observe scope pattern and check for low spark plug firing voltage and pattern. See Fig 5. If spark plug firing voltage is inconsistent (low on one or more cylinders), go to next step. If spark plug firing voltage is consistently low or a sloped spark line is present in one or more cylinders, check spark plug wires and spark plugs on affected cylinders. Measure resistance of spark plug wires. Spark plug wire resistance should be 7 k/ohms or less per foot. Measure resistance of spark plugs. Spark plug resistance should be 2-20 k/ohms. Repair as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair.
    Fig 5: Identifying Low Spark Plug Firing Voltage
    G00088376Courtesy of FORD MOTOR CO.

  9. 9) Check For Uneven Spark Plug Firing Voltage Between Cylinders

    Observe scope pattern and check for uneven spark plug firing voltage and pattern. See Fig 6. If spark plug firing voltage variation is more than 6 kilovolts, check spark plug wires and spark plugs on affected cylinders. Measure resistance of spark plug wires. Spark plug wire resistance should be 7 k/ohms or less per foot. Measure resistance of spark plugs. Spark plug resistance should be 2-20 k/ohms. Repair as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plug firing voltage variation is 6 kilovolts or less, fault is unable to be duplicated at this time. Go to TEST Z, step 1) .
    Fig 6: Checking For Uneven Spark Plug Firing Voltage Between Cylinders
    G00088377Courtesy of FORD MOTOR CO.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 9) to step 15). No test procedures have been omitted.

  10. 15) DTC P0301-P0310: Misfire On Cylinders No. 1-10

    If DTC P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0309 or P0310 is present, go to next step. If specified DTCs are not present, go to step  17).

  11. 16) Check For Spark At Cylinder(s) Indicated By DTC(s)

    Disable Inertia Fuel Shutoff (IFS) switch. Disconnect ignition coil(s) from spark plug(s). Connect Air Gap Spark Tester (303-D037) to suspect coil(s). Check for spark at cylinder(s) while cranking engine. If Blue-White spark is present, turn ignition switch to OFF position and go to step  18). If Blue-White spark is not present, check coil boots of missing cylinders. Replace as necessary. If boots are okay, measure resistance of spark plug(s). If resistance is not 2-20 k/ohms, replace affected spark plug(s) and go to TEST JF, step 1) .

  12. 17) Check For Spark At All Cylinders

    Disable Inertia Fuel Shutoff (IFS) switch. Disconnect ignition coil(s) from spark plug(s). Install Air Gap Spark Tester (303-D037) to suspect coil(s). Check for spark at all cylinders while cranking engine. If Blue-White spark is consistent between all cylinders, turn ignition switch to OFF position and go to next step. If Blue-White spark is not consistent between all cylinders, check coil boots of missing cylinders. Replace as necessary. If boots are okay, measure resistance of spark plug(s). If resistance is not 2-20 k/ohms, replace affected spark plug(s). Note cylinders with inconsistent spark and go to TEST JF, step 1) .

  13. 18) Check Spark Plugs

    Remove and inspect spark plugs for damage, wear, carbon deposits and proper plug gap. Adjust gap or replace plugs as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plugs are okay, go to next step.

  14. 19) Check Spark Plug Resistance

    Measure resistance of spark plugs. If resistance is not 2-20 k/ohms, replace faulty spark plug. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plug resistance is within specification, proceed as follows:
    • If misfire is intermittent, go to TEST Z, step 1) .
    • If directed here from SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article, return to symptom test that directed you here.
    • If directed here from TEST HD, step  3), go to TEST HD, step  4).
    • If directed here from TEST A, step 6) , return to TEST A, step 6) .

  15. 20) DTC P0301-P0310: Misfire On Cylinders No. 1-10

    If DTC P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0309 or P0310 is present, go to next step. If specified DTCs are not present, go to step  22).

  16. 21) Check For Spark At Cylinders Indicated By DTCs

    Disable Inertia Fuel Shutoff (IFS) switch. Disconnect spark plug wire(s) from spark plug(s). Install Air Gap Spark Tester (303-D037) to suspect spark plug wire. Check for spark from suspect spark plugs while cranking engine. If Blue-White spark is present, turn ignition switch to OFF position and go to step  23). If Blue-White spark is not present, measure resistance of spark plug wire to missing cylinder(s). Spark plug wire resistance should be 7 k/ohms or less per foot. Repair as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plug wire resistance is within specification, go to TEST JE, step 1) .

  17. 22) Check For Spark At All Spark Plugs

    Disable Inertia Fuel Shutoff (IFS) switch. Disconnect spark plug wires from spark plugs. Install Air Gap Spark Tester (303-D037) to suspect spark plug wire. Check for spark from each spark plug while cranking engine. If Blue-White spark is consistent between all cylinders, turn ignition switch to OFF position and go to next step. If Blue-White spark is inconsistent between cylinders, measure resistance of spark plug wire to missing cylinder(s). Spark plug wire resistance should be 7 k/ohms or less per foot. Repair as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plug wire resistance is within specification, go to TEST JE, step 1) .

  18. 23) Check Spark Plugs

    Remove and inspect spark plugs for damage, wear, carbon deposits and proper plug gap. Adjust spark plug gap or replace spark plug(s) as necessary. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plugs are okay, go to next step.

  19. 24) Check Spark Plug Resistance

    Measure resistance of spark plugs. If resistance is not 2-20 k/ohms, replace faulty spark plug. Perform DRIVE CYCLES . Ensure MISFIRE & FUEL MONITOR PROCEDURES are performed to verify repair. If spark plug resistance is within specification, proceed as follows:
    • If concern is intermittent, go to TEST Z, step 1) .
    • If directed here from SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article, return to symptom test that directed you here.
    • If directed here from TEST HD, step  3), return to TEST HD, step  4).
    • If directed here from TEST A, step 6) , return to TEST A, step 6) .
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