Test Procedure

• Ignition ON, engine OFF.
• Clear the PCM DTCs.
• Clear the SOBDMC DTCs.

Have the DTCs been cleared? 

• A list of related PIDs and signals are needed for use with the scan tool to monitor the suspect areas. Obtain the customer symptom description. Use the Reference Value Symptom chart and proceed to the Reference Value PID or Signal Measurement chart located at TYPICAL DIAGNOSTIC REFERENCE VALUES .
• Highlight each available PID and signal recommended by the charts under the PID and signal selection menu on the scan tool.

Have all available PIDs and signals related to the symptom been selected? 

• The vehicle is in for a repeat repair.
• No DTC is present.
• Customer has difficulty describing the symptom.

Has a symptom been detected? 

• Prepare the freeze frame data for use with information from the Symptom Charts in the Engine Controls Symptom Charts article.
• Check the continuous memory DTCs that should have been recorded from an earlier pinpoint test.
• Access information from the customer information worksheet and the customer if available. Access any other symptom related data available, such as TSBs and CQIS reports.

Has all available data been recorded? 

• With the scan tool, select and monitor the same PIDs as displayed in freeze frame along with previously selected PIDs and signals from Step Z2. Using freeze frame data recorded earlier, recreate the conditions described by each freeze frame PID. Pay special attention to ECT, LOAD, RPM and VSS. Use any available data from the customer, TSBs, 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.

Could the symptom be recreated? 

• 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 and signals with a scan tool and circuit measurements with a DMM. This is done under 4 different conditions - key on/engine off, hot idle, 48 km/h (30 mph) and 88 km/h (55 mph). Use the typical diagnostic reference values from the Engine Controls Reference Values article to compare with the actual vehicle.
• Locate the correct Reference Value Chart in the Engine Controls Reference Values article.
• Setup the vehicle to measure the circuits with a DMM and a scan tool.
• Connect the scan tool to the data link connector (DLC).
• Ignition ON, engine OFF.
• With the scan tool, select and monitor PIDs and measure circuits shown in the Reference Value Chart in the Engine Controls Reference Values article.
• Compare the scan tool PIDs and digital multimeter values to the Reference Value Charts.

Are any values out of range? 

• The engine temperature should be at least 87°C (189°F).
• Ignition ON, engine running.
• Continue to monitor the PIDs and circuits as in the previous step.

Are any values out of range? 

• Drive the vehicle on a preplanned route.
• Continue to monitor the PIDs 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 PIDs and circuits as in the previous step.

Are any values out of range? 

• Remain in the PID and Signal selection menu with the scan tool.
• If the intermittent road test step was used to verify the symptom, highlight the PIDs and signals that were displayed as a mismatch to the Reference Values from the Engine Controls Reference Values article. Otherwise, highlight only the PIDs and signals from step Z2.
• Proceed to the Intermittent Test chart located at the beginning of this pinpoint test.
• Match the selected PIDs and signals to the corresponding circuit in the chart. There may be more than one circuit to test. If a PID or 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.
• Input Test - used on sensing inputs such as temperature, position or oxygen.
• Output Test - used on output devices such as relays, coils or solenoids.

Has a test been chosen? 

• Using the circuits chosen from the Intermittent Test Chart, select only the recommended PIDs and 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, engine OFF.
• If the input is a switch type-component, turn it on manually.
• Monitor the PID or DMM while tapping on the component.
• Monitor while wiggling the sensor harness wire from the component to the PCM or TCM.
• Look for abrupt changes in the values. Compare these actual values to the TYPICAL DIAGNOSTIC REFERENCE VALUES .

Are there abrupt changes in the PID values that do not compare with the Engine Controls Reference Values article readings? 

• Ignition ON, engine running.
• Continue to monitor the PIDs 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 while tapping on the component.
• Monitor while wiggling the sensor harness wire from the component to the PCM or TCM.
• Look for abrupt changes in the values. Compare these actual values to the TYPICAL DIAGNOSTIC REFERENCE VALUES .

Are any values fluctuating in and out of range? 

• Ignition ON, engine OFF.
• Continue to monitor the PIDs 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 DDM values while lightly spraying a water mist on the component to PCM or TCM.
• Monitor while spraying the sensor harness wire from the component to the PCM or TCM.
• Look for abrupt changes in the values. Compare these actual values to the TYPICAL DIAGNOSTIC REFERENCE VALUES .

Are any values fluctuating in and out of range? 

• Ignition ON, engine running.
• Continue to monitor the PIDs 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 to PCM.
• 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 TYPICAL DIAGNOSTIC REFERENCE VALUES .

Are any values fluctuating in and out of range? 

• Using the circuits chosen from the Intermittent Test Chart, select only the recommended PIDs and signals to monitor with the scan tool. If a PID is not available for the circuit, use a digital multimeter to check the value.
• Ignition ON, engine OFF.
• 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 while tapping on the component.
• Monitor while wiggling the sensor harness wire from the component to the PCM or TCM.
• Look for abrupt changes in the values. Compare these actual values to the TYPICAL DIAGNOSTIC REFERENCE VALUES .

Is there a mismatch between command and actual, or are any values fluctuating in and out of range when compared to the Reference Value Charts in the Engine Controls Reference Values article? 

• Ignition ON, engine running.
• Proceed to the area of the suspect wiring or component concern.
• Monitor the PIDs with the scan tool and note the values. Compare the scan tool values with values from a DMM with the engine at idle. Look for fluctuations in the values while tapping on the suspect component.
• 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 PIDs while wiggling the sensor harness wire from the component to the PCM.
• Look for abrupt changes in the values. Compare these actual values to the TYPICAL DIAGNOSTIC REFERENCE VALUES .

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

• Ignition ON, engine OFF.
• 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 to PCM.
• Look for abrupt changes in the values. Compare these actual values to the TYPICAL DIAGNOSTIC REFERENCE VALUES .

Is there a mismatch between command and actual or are any values fluctuating in and out of range when compared to the Reference Value Charts in the Engine Controls Reference Values article? 

• Ignition ON, engine running.
• Using the circuits chosen from the Intermittent Test Chart, select only the recommended PIDs and signals to monitor with the scan tool. If a PID is not available for the circuit, use a digital multimeter 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 to PCM.
• 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 TYPICAL DIAGNOSTIC REFERENCE VALUES .

Is there a mismatch between command and actual or are any values fluctuating in and out of range when compared to the Reference Value Charts in the Engine Controls Reference Values article? 

• An inspection of DTC related mechanical systems should have been performed in an earlier article. 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 or transmission gear changes, acceleration and deceleration, rough roads, and various engine RPM and torque related conditions.

Is a mechanical concern detected?