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System Tests: Intermittent

NOTE: Perform first test step only if PCM reset was not done earlier, otherwise go to step  2 . Eliminating FMEM will insure reproduction of any PCM related symptom.

  1. Perform PCM Reset To Clear FMEM

    Connect scan tool to DLC. Record freeze frame data before resetting PCM. With KOEO, complete a PCM reset. If PCM reset is complete, go to next step. If PCM reset is not complete, complete PCM reset. Go to next step.

  2. Select PIDs Related To The Symptom

    A list of PIDs is needed for use with scan tool to indicate area of fault. Highlight each PID related to symptom. If all PIDs related to symptom have been chosen, go to next step. If all PIDs related to symptom have not been chosen, repeat this test step.

  3. Decision To Verify Symptom

    The path to symptom verification is optional, but is recommended for several reasons. Some reasons are:
    • Vehicle is in for repeat repair.
    • No DTC is present.
    • Customer has difficulty describing symptom.
    If symptom needs to be verified, go to next step. If symptom does not need to be verified, go to step  10 .
    NOTE: Only MIL codes will trigger freeze frame data.

  4. Collect Any Available Data To Aid In Symptom Verification

    Prepare freeze frame data for use that was recorded earlier. Continuous Memory DTCs should already be recorded from an earlier test. Access any other available data from the customer. If all data has been recorded, go to next step. If all data has not been recorded, gather as much data as possible to help in isolation of intermittent fault area. Repeat this test step.
    NOTE: Vehicle may need to be driven to proceed with next test step. Concern must be verified by re-creating conditions that originally set DTC.

  5. Re-Create Symptom Using All Data

    Using scan tool, select and monitor the same PIDs as displayed in freeze frame along with the previous highlighted PIDs from step  2 . Using freeze frame data recorded earlier, re-create conditions described by each freeze frame PID. Pay particular attention to ECT, load, RPM and VSS. Also use any available customer data to help in producing the correct conditions for re-creating the symptom. When symptom occurs, press trigger to begin recording. If symptom is reproduced, go to step  10 . If symptom is not reproduced, go to next step.

  6. Re-Create Symptom Using KOEO Road Test Procedure

    The road test is the last attempt to locate area of concern before physically disturbing vehicle wiring harness. PIDs for outputs represent commanded values only. Circuit measurements with DVOM indicate actual output status. Therefore, the PID and circuit reading may not correspond with each other. PIDs to PCM inputs with a mismatch to the circuit measurement indicate a possible PCM concern. The intermittent road test procedure is a set of instructions for monitoring PIDs with a scan tool. Monitoring is performed under 4 different conditions: KOEO, hot idle, 30 MPH 55 MPH. Use PID/DATA MONITOR to compare with actual vehicle values. For 30 MPH and 55 MPH procedures, a planned route with a passenger is required. Locate corresponding PIN/PID Chart. See PIN VOLTAGE/PID VALUE CHARTS article. Set vehicle up to measure circuits with a DVOM. Connect scan tool to DLC. With KOEO, select and monitor PIDs and also measure circuits shown in PIN/PID Chart. Compare scan tool PIDs and DVOM values to values listed in PIN VOLTAGE/PID VALUE CHARTS article. If any value is out of range, go to step  10 . If all values are within specification, go to next step.

  7. Re-Create Symptom Using Hot Idle Road Test Procedure

    With ignition on or KOER, with engine coolant temperature 195°F (87°C), continue to monitor the same PIDs and circuits as in the previous test step at hot idle. If any values are out of range, go to step  10 . If values are not out of range, go to next step.

  8. Re-Create Symptom Using 30 MPH Slow Cruise Road Test Procedure

    Drive vehicle on a preplanned route. Continue to monitor the same PIDs and circuits during slow cruise as in the previous test step. If any values are out of range, go to step  10 . If values are not out of range, go to next step.

  9. Re-Create Symptom Using 55 MPH High Cruise Road Test Procedure

    Continue to drive vehicle on a preplanned route. Continue to monitor the same PIDs and circuits during high cruise as in the previous test step. If any values are out of range, go to next step. If values are not out of range, physically disturb selected vehicle wiring harness in an attempt to re-create intermittent concern. Go to next step.

  10. Select Circuits From PID/Data Monitor Table

    Remain in PID section of scan tool menu. If intermittent road test was used to verify symptom, highlight PIDs or signals that displayed a mismatch to values listed in PIN/PID Chart. Otherwise, highlight only PIDs from step  2 . Match selected PIDs to corresponding circuit in PIN/PID Chart. There may be more than one circuit to test. If a PID recording was made with a scan tool, it may be helpful to replay at this time. From PIN/PID Chart, select and proceed to appropriate test:
    • Input Test is used on sensing devices such as temperature, position or oxygen.
    • Output Test is used on output devices such as relays, coils or solenoids.
    If a test has been chosen, for Input Test, go to next step or for Output Test, go to step  15 . If a test has not been chosen, to diagnose other driveability symptoms, see TROUBLE SHOOTING - NO CODES article.
    WARNING: When performing next test step, always be aware of hands, clothing and tools near cooling fans, moving parts and hot surfaces.

  11. KOEO Input Test Procedure For PCM Sensors

    Using circuits chosen from PIN/PID Chart, select only recommended PIDs to monitor with scan tool. If a PID is not available for the circuit, use a DVOM. Proceed to the suspect wiring harness area or component. If input is a switch-type component, turn on manually. Monitor PID or DVOM values while tapping on component. Monitor while wiggling sensor harness wire from component to PCM. Look for abrupt changes in values. Compare actual values to KOEO PID values. See PIN VOLTAGE/PID VALUE CHARTS article. If values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.

  12. KOER Input Test Procedure For PCM Sensors

    Repeat step  11 under KOER. If any values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.

  13. KOEO Water Soak Test Procedure For PCM Sensors

    With KOEO, using scan tool, continue to monitor PIDs or circuits. Proceed to the suspect wiring harness area or component. If input is a switch-type component, turn on manually. Monitor PID or DVOM values while lightly spraying water on component. Monitor while spraying sensor harness wire from component to PCM. Look for abrupt changes in values. Compare actual values to KOEO PID values. See PIN VOLTAGE/PID VALUE CHARTS article. If values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.

  14. KOER Water Soak Test Procedure For PCM Sensors

    Repeat step  13 under KOER. If any values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.
    NOTE: PIDs selected from PIN/PID Chart will display commanded values only. DVOM measurements will display actual values.
    WARNING: During the remainder of test procedure, cooling fans or fuel pump may turn on.

  15. KOEO Output Test Procedure For PCM Actuators

    Using scan tool, using circuits chosen from PIN/PID Chart, select recommended PID(s) to monitor. Also, use a DVOM to compare circuit values with scan tool PID values. If PIDs are not available for a particular circuit, look for a DVOM fluctuation to occur. Output Test Mode may not control some outputs, such as injectors and ignition coils. To test these output types, go to next step. Using scan tool, turn on all outputs. Proceed to area of suspect wiring harness or component fault. Monitor PID and DVOM values while tapping on component. Monitor while wiggling wiring harness from component to PCM. Look for abrupt changes in values. Compare actual values to KOEO PID values. See PIN VOLTAGE/PID VALUE CHARTS article. If values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.

  16. KOER Output Test Procedure For PCM Actuators

    With KOER, proceed to area of suspect wiring harness or component fault. Using scan tool, monitor PIDs (if available). Compare DVOM values with scan tool values or look for a fluctuation in idle while tapping on component. If a coil has been tapped and is suspect, turn ignition off. It may be helpful to remove suspect ignition coil and measure continuity from spark plug terminal to signal terminal while tapping coil. A large fluctuation in resistance will indicate an intermittent open. Otherwise, monitor while wiggling wiring harness from component to PCM. Look for abrupt changes in values. Compare actual values to HOT IDLE PID/DATA MONITOR values. See PIN VOLTAGE/PID VALUE CHARTS article. If values are fluctuating at idle or DVOM values are mismatched or fluctuate, repair as necessary. If values are not fluctuating at idle or DVOM values are not mismatched or fluctuate, go to next step.

  17. KOEO Water Soak Test Procedure For PCM Actuators

    With KOEO, using scan tool, turn on all outputs. Output Test Mode may not control some outputs, such as injectors. To test these output types, go to next step. Proceed to area of suspect wiring harness or component fault. Monitor PID and DVOM value while spraying a light mist of water on the component. Continue to monitor while spraying wiring harness from component to PCM. Look for abrupt changes in values. Compare actual values to KOEO PID values. See PIN VOLTAGE/PID VALUE CHARTS article. If values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.

  18. KOER Water Soak Test Procedure For PCM Actuators

    Repeat step  17 with KOER. If values are fluctuating in and out of range, repair as necessary. If values are not fluctuating in and out of range, go to next step.

  19. Inspect For Intermittent Mechanical Concerns

    It is possible for an intermittent mechanical fault to cause a good PCM system to react abnormally. An inspection of mechanical systems relating to DTC or symptom should have been performed in an earlier procedure. If a mechanical system inspection has not been performed, inspect at this time. Check for wires that may short and vacuum lines or hoses that may kink causing:
    • Engine rock during acceleration.
    • Components moving during high RPM or rough road.
    • Accelerator or transmission linkage contact/interferance.
    If a mechanical problem is found, repair as necessary. If a mechanical problem is not found, unable to verify fault at this time.
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