How To Use The Diagnostic Procedures
- Use the information about the vehicle driveability or emission concern (from the write-up or Customer Information Worksheet) to attempt to verify/re-create the symptom. Look for any vehicle modifications or aftermarket items that may contribute to the symptom. A check of any applicable TSBs may be useful, if this information is available.
- Go to QT: POWERTRAIN CONTROL MODULE (PCM) QUICK TEST . Carry out the PCM Quick Test.
- If the PCM Quick Test is completed and no DTCs were retrieved, go to the NO DTCS PRESENT SYMPTOM CHART INDEX .
- Select the symptom that best describes the vehicle symptom (for multiple symptoms select the one that is most evident). Go to the No DTCs Present Symptom Chart Index that is indicated. If no PCM DTCs are present and the vehicle symptom is not listed in the No DTCs Present Symptom Chart Index, go to the appropriate service information article to continue diagnosis.
- The No DTCs Present Symptom Chart contains areas to be tested for diagnosis of the vehicle symptom. The chart is arranged to place the higher probability or easiest to test items toward the top of the chart. However, the technician is not required to follow this order due to reasons such as variations in vehicle type, vehicle repair history, or technician experience.
- Follow the instructions in the step (including Preliminary Checks)
- The System/Component column indicates the areas that will be tested. This column may also contain a quick system/component test.
- If a quick system/component test is in the System/Component column, the Reference column will indicate where to go if the test failed.
- If the step contains a test procedure or question (without a reference outside the step), carry out the test step/answer the question and continue as directed.
- The Reference column indicates where to go for the System/Component testing. If the step sends you to a specific area for testing (for example Hard Start/No Start Procedures, a pinpoint test step in this article or a service information article), go to the procedures. Follow the directions given in those procedures, including directions to other tests or service information article. If a fault is found, repair/replace as directed. If no fault is found and diagnosis in that area is complete, return to the Symptom Chart and continue as directed.
- During diagnosis, if directed to test a system/component that is not contained on that vehicle, go to the next step.
- If the Symptom Chart for the vehicle symptom is completed and no fault is found, return to the Symptom Chart Index to address the next most prominent symptom.
- After repair, restore the vehicle by reconnecting any components and removing any test equipment. Verify that the vehicle is operating properly and the original complaint is eliminated. If a DTC was present, repeat the Quick Test to verify the repair and clear any Continuous Memory DTCs.
NOTE:
If a symptom is determined to be intermittent, careful visual and physical underhood inspection of connectors, wiring harnesses, vacuum lines, and components is required. The Customer Information Worksheet may contain more detailed symptom information. Before an in-depth diagnosis begins, start the engine wiggle wires and tap on components while listening for an indication of a concern (such as an RPM change or a relay clicking).
Information about engine conditions is stored when a DTC that illuminates the malfunction indicator lamp (MIL) is set.