Step 4: Road Test

Re-Creating the Symptom

In order to diagnose an intermittent symptom, one must re-create the symptom and collect information on how the EEC system is sensing and reacting. After visual and non-EEC checks are completed and satisfied, the EEC portion is diagnosed. Through the use of the DATA MONITOR AND RECORD function these signal lines can be inspected. In addition, the information received from the DATA MONITOR AND RECORD function can reveal the presence of mechanical problems.

Road Test Set-Up

1. List the PCM sensors and actuators that could cause the condition. These signals will be monitored during the road test.

Diagnostic Reference Value Sheet:

2. Refer to the Diagnostic Reference Value Sheet. This sheet lists PCM sensor and actuator values at various operating conditions. The values given on these sheets are "ballpark" references only.
3. In order for a road test to be performed another person must accompany the driver. This is a safety issue because the driver should not divert his attention to the operation of the test equipment. The accompanying person can select signals, observe changes and record notes.
4. The accompanying passenger should hold the NGS Scan Tool. If the NGS Scan Tool is powered by the battery, secure the battery power hookup adapter.

Road Test Reminders

The purpose of the road test is to re-create the problem symptom by duplicating the conditions that caused it to occur.

Alternatives. In some cases it may not be necessary or desirable to perform an actual road test. The symptom may occur at starting, idle or high rpm idle conditions. If this situation applies, proceed with the Road Test Procedure by using the operating condition that applies the most to your situation.

Legality/Liability. The Road Test Procedure is a suggested and optional part of this section. The liability of this operation is left to the individual who chooses to use it.

Safety. It is important that the road test is performed with safety issues in mind. Use the vehicle seat belts and operate the vehicle in a safe manner.

Road Test Observations

During the road test, various PCM signals are chosen and their values shown. In addition, there is other important information that can be viewed during the road test, including:

EEC Graphs And Charts:

- PCM Values. Compare road test values at various operating conditions with those listed in the Diagnostic Reference Value Sheet. Refer to EEC Graphs and Charts in image for further detail.

- Real Time Diagnosis. By using the DATA MONITOR AND RECORD function, in Key On Engine Off (KOEO) or in Key On Engine Running (KOER), often an intermittent failure of any Diagnostic Test Mode item will trigger the beeper. The NGS Scan Tool will beep once and display the faulty component after recording and storing of data are complete.

NOTE: Real Time Diagnosis is also available in Key On Engine Off.

Road Test Procedure

1. Start the vehicle.
2. Select all PCM sensors and actuators in DATA MONITOR AND RECORD.
3. Set RECORDER AREA to 1,2,3, or 4.
4. Set RECORDER MODE to MANUAL.
5. Set RECORDER RATE to FAST.
6. Drive the vehicle to create conditions so that the symptom occurs.
7. When the symptom occurs, the accompanying passenger should press the START key (number 6) and follow the instructional messages on the screen display. He/she should observe changes in the first PCM signal that could cause the symptom. Specific notes about the symptom, device, or operating conditions should be recorded onto paper.
8. The drive symptom can be created and recorded again in another RECORDER AREA for confirmation. Otherwise, the road test is completed and you can return to analyze the results.