Pinpoint Test Z: Intermittent

This pinpoint test is intended to diagnose and isolate intermittent concerns for all EEC subsystems. Parameter identifiers (PIDs) corresponding to a circuit can be used to aid in identifying the intermittent cause. Some circuits do not have an associated PID or the PID may not be available and must be measured using a digital multimeter.

Refer to the appropriate DTC Fault Trigger Conditions.

DTC Fault Trigger Conditions 

Possible Causes 

• Wiring, terminals, or connectors
• Mechanical concern
• Suspect sensor concern

• NOTE: Proceed with this step only if the PCMDTCs and the freeze frame data have not been cleared. Record freeze frame data prior to clearing the PCMDTCs. Clearing the DTCs clears any freeze frame data and eliminates FMEM. This helps to recreate the original conditions that set the DTCs or caused the symptom.

• Refer to the Reference Value PID/Signal Measurement chart located at the beginning of article 303-14, Electronic Engine Controls, Specifications. Record each available PID/signal and the PID value recommended by the charts under the PID/signal selection menu for selection on the scan tool.

• Ignition ON.

• Clear the PCMDTCs.

Are the PCM DTCs cleared? 

• A list of related PIDs and/or signals are needed for use with the scan tool to monitor the suspect areas. Obtain the customer symptom description. Use the previously selected PIDs/signals from step Z1.

• Highlight each available PID /signal recommended by the charts under the PID /signal selection menu on the scan tool.

Are all available PIDs /signals related to the symptom selected? 

• NOTE: The path to symptom verification is optional but is recommended for several reasons. For example, the vehicle is back for a repeat repair, or there is no DTC present.

Is a concern or symptom present? 

• NOTE: Only MIL codes trigger freeze frame data. Refer to the scan tool instruction manual to retrieve the freeze frame information.

• Prepare the freeze frame data for use with information from the Symptom Charts.

• Check for continuous memory DTCs that should have been recorded from an earlier pinpoint test.

• Access the information from the customer information worksheet and the customer if available. Access any other symptom related data available, such as TSB s and OASIS reports.

Is all available data recorded? 

• NOTE: To recreate the original conditions that set the DTC or caused the symptom, the vehicle may require driving.

• With the scan tool, select and monitor the same PID s as displayed in freeze frame along with any previously selected PID s/signals from step Z1. Using the freeze frame data recorded earlier, recreate the conditions described by each freeze frame PID. Pay special attention to ECT, LOAD, RPM and VSS. Also, use any available data from the customer, TSB s, and other sources to aid in producing the correct conditions for recreating the symptom.

• When the symptom occurs, press the trigger to begin recording. Refer to the scan tool instruction manual for information on the recorder function.

Can the symptom be recreated? 

• NOTE: PID s for output in the Reference Value Charts represent command values only. Circuit measurements with a DMM indicate the actual output status. Therefore, in the case of a concern, the PID and circuit reading on the vehicle may not correspond with each other.

• The road test is the last attempt to locate the area of concern before physically disturbing vehicle circuits.

• The Intermittent Road Test Procedure is a set of instructions for monitoring PIDs /signals with a scan tool and circuit measurements with a DMM. This is done under 4 different conditions - ignition on and engine off, hot idle, 48 km/h (30 mph) and 88 km/h (55 mph). Use the typical diagnostic reference values previously recorded from step Z1 to compare with the actual vehicle.

• Setup the vehicle to measure the circuits with a DMM and a scan tool.

• Connect a scan tool to the DLC.

• Ignition ON.

• With the scan tool, select and monitor PID s and measure the circuits previously selected from step Z1.

• Compare the scan tool PID s and DMM values to the reference value charts.

Are any values out of range? 

• NOTE: The engine temperature should be at least 87°C (189°F).

• Start the engine.

• Continue to monitor the PID s and circuits as in the previous step.

Are any values out of range? 

• Drive the vehicle on a preplanned route.

• Continue to monitor the PID s and circuits as in the previous step.

Are any values out of range? 

• Continue to drive the vehicle on the preplanned route.

• Continue to monitor the PID s and circuits as in the previous step.

Are any values out of range? 

• NOTE: From the same chart, be sure to select and proceed with the appropriate test type.

• NOTE: The Input Test step should be used on sensing inputs such as temperature, position or oxygen.

• NOTE: The Output Test step should be used on output devices such as relays, coils or solenoids.

• Remain in the PID /Signal selection menu with the scan tool.

• Highlight only the PID s/signals from step Z1.

• Match the selected PID s/signals to the corresponding circuit previously selected from step Z1. There may be more than one circuit to test. If a PID /signal recording was made with the scan tool, it may be helpful to replay it at this time. Refer to the scan tool instruction manual for additional information.

Has a test been chosen? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces. Failure to follow these instructions may result in personal injury.

• Using the circuits chosen from the previously selected PIDs/signals from step Z1, select only the recommended PIDs/signals to monitor with the scan tool. If a PID is not available for the circuit, use a DMM to check the value.

• Proceed to the area of the suspect wiring or component concern.

• Ignition ON.

• If the input is a switch type-component, turn it on manually.

• Monitor the PID or DMM and wiggle the sensor harness wire from the component to the PCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Are there abrupt changes in the PID values that do not compare with the previously selected PIDs/signals from step Z1? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces. Failure to follow these instructions may result in personal injury.

• Start the engine.

• Continue to monitor the PID s and circuits as in the previous step.

• Proceed to the area of the suspect wiring or component concern.

• If the input is a switch type-component, turn it on manually.

• Monitor the PID or DMM and wiggle the sensor harness wire from the component to the PCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Are any values fluctuating in and out of range? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces. Failure to follow these instructions may result in personal injury.

• Ignition ON.

• Continue to monitor the PID s and circuits as in the previous step.

• Proceed to the area of the suspect wiring or component concern.

• If the input is a switch type-component, turn it on manually.

• Monitor the PID or DMM values while lightly spraying a water mist on the component.

• Monitor while spraying the sensor harness wire from the component to the PCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Are any values fluctuating in and out of range? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces.

  Failure to follow these instructions may result in personal injury. 

• Start the engine.

• Continue to monitor the PID s and circuits as in the previous step.

• Proceed to the area of the suspect wiring or component concern.

• If the input is a switch type-component, turn it on manually.

• Monitor the PID or DMM values while lightly spraying a water mist on the component.

• Monitor while spraying the sensor harness wire from the component to the PCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Are any values fluctuating in and out of range? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces. Failure to follow these instructions may result in personal injury.

• NOTE: Remember that PID s previously selected from step Z1 display commanded values only. A DMM measurement is needed to display the actual values. Be sure to compare them. Look for fluctuations to occur during any part of the following test. The output state test may not control some outputs, such as injectors and ignition coils and may not be available for all actuators.

• Using the circuits chosen from the previously selected PIDs/signals from step Z1, select only the recommended PIDs/signals to monitor with the scan tool. If a PID is not available for the circuit, use a DMM to check the value.

• Ignition ON.

• With the scan tool, turn on selected outputs using output state control. Refer to the scan tool instruction manual.

• Proceed to the area of the suspect wiring or component concern.

• Monitor the PID or DMM and wiggle the sensor harness wire from the component to the PCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Is there a mismatch between command and actual, or are any values fluctuating in and out of range, when compared to the previously selected PIDs/signals from step Z1? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces. Failure to follow these instructions may result in personal injury.

• NOTE: Remember that PID s previously selected from step Z1 display commanded values only. A DMM measurement is needed to display the actual values. Be sure to compare them. Look for fluctuations to occur during any part of the following test. The output state test may not control some outputs, such as injectors and ignition coils and may not be available for all actuators.

• Start the engine.

• Proceed to the area of the suspect wiring or component concern.

• Monitor the PID s with the scan tool and note the values. Compare the scan tool values with values from a DMM with the engine at idle.

• If a coil for a coil on plug application is suspect, turn off the ignition. Gain access to the coil and measure continuity from the spark plug terminal to the signal terminal while tapping the coil. A large fluctuation in resistance indicates an intermittent open or short.

• Monitor the PID and wiggle the sensor harness wire from the component to the PCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Is there a scan tool to DMM value mismatch or an idle fluctuation? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces. Failure to follow these instructions may result in personal injury.

• NOTE: Remember that PID s previously selected from step Z1 display commanded values only. A DMM measurement is needed to display the actual values. Be sure to compare them. Look for fluctuations to occur during any part of the following test. The output state test may not control some outputs, such as injectors and ignition coils and may not be available for all actuators.

• Ignition ON.

• With the scan tool, turn on selected outputs using output state control. Refer to the scan tool instruction manual.

• Proceed to the area of the suspect wiring or component concern.

• Monitor the PID or DMM values while lightly spraying a water mist on the component.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Is there a mismatch between command and actual, or are any values fluctuating in and out of range, when compared to the previously selected PIDs/signals from step Z1? 

• WARNING: When carrying out any test steps, always be aware of hands, clothing or tools near cooling fans, belts or hot surfaces.

  Failure to follow these instructions may result in personal injury. 

• Start the engine.

• Using the circuits chosen from the previously selected PIDs/signals from step Z1, select only the recommended PIDs/signals to monitor with the scan tool. If a PID is not available for the circuit, use a DMM to check the value.

• Proceed to the area of the suspect wiring or component concern.

• Monitor the PID or DMM values while lightly spraying a water mist on the component.

• Monitor while spraying the sensor harness wire from the component to the PCM / TCM.

• Look for abrupt changes in the values. Compare these actual values to the previously selected PIDs/signals from step Z1.

Is there a mismatch between command and actual, or are any values fluctuating in and out of range, when compared to the previously selected PIDs/signals from step Z1? 

• NOTE: It is possible for an intermittent mechanical concern to cause a good PCM system to react abnormally.

• An inspection of DTC related mechanical systems should have been carried out in an earlier procedure. If not, visually inspect at this time.

• Look for possible vacuum lines, wires, cables, linkage or hoses that may become kinked, shorted or restricted during normal engine operation.

• This may include engine/transmission gear changes, acceleration and deceleration, rough roads and various engine RPM and torque related conditions.

Is a mechanical concern detected?