How to Use the Diagnostic Procedures

HOW TO USE THE DIAGNOSTIC PROCEDURES

- Use the information about the vehicle driveability or emission concern 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 or OASIS messages may be useful, if this information is available.
- Go to Symptom Charts, Step 1: PCM Quick Test. Carry out the PCM Quick Test step(s). Follow any notes as directed. QT Step 1: Powertrain Control Module (PCM) Quick Test
- If PCM Quick Test is completed, no DTCs were retrieved and no special notes applied, go to Step 2: No DTCs Present Symptom Chart Index. Step 2: No DTC(s) 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 Step 3: No DTCs Present Symptom Chart 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 Vehicle System to continue diagnosis. Step 3: No DTC(s) Present Symptom Charts
- The No DTCs Present Symptom Charts contain 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. The technician, however, is not required to follow this order due to reasons such as variations in vehicle type, vehicle repair history or technician experience.
- The System/Component column indicates the areas that will be tested. This column may also contain a quick system/component test.
- The Reference column indicates where to go for the System/Component testing. All references are to the beginning of a pinpoint test or pinpoint test steps in Pinpoint Tests unless noted otherwise. If referred to a Pinpoint Test Step in Computers and Control Systems or Vehicle Systems, go to the procedures. Follow the directions given in those procedures, including directions to other tests or Systems. If a damaged part is found, repair as directed. If no fault is found, and diagnosis in that area is complete, return to the No DTCs Present Symptom chart and continue to the next item.
- If a quick system/component test is in the System/Component column, the reference column will indicate where to go if the test failed.

- During diagnosis, if directed to test a system/component that is not contained on that vehicle, proceed to the next step.
- If the No DTCs Present Symptom Chart for the vehicle symptom is completed and no fault is found, return to Step 2: No DTCs Present Symptom Chart Index to address the next most prominent symptom. If all diagnosis is complete and no fault is found, it may be helpful to go to Pinpoint Tests, Pinpoint Test Step Z, for further diagnosis. Step 2: No DTC(s) Present Symptom Chart Index Test Z: Intermittent

NOTE: The installation of any new component that affects the powertrain control module (PCM) adaptive learning strategies (idle speed, refueling event, or fuel trim) requires the reset of keep alive memory (KAM). Refer to Diagnostic Methods, Resetting the Keep Alive Memory (KAM).

- After repair, restore vehicle by reconnecting any components and removing test equipment. Verify that the vehicle is operating properly and the original complaint is no longer present. If a DTC was present, clear the DTCs and repeat the self-test to verify the repair.

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 and wiggle wires, tap on components while listening for an indication of a concern (such as RPM change or relay clicking).

Information about engine conditions is stored when a DTC that illuminates the Malfunction Indicator Lamp (MIL) is set. This information is called Freeze Frame Data and may be helpful in diagnosing intermittent concerns. Refer to Diagnostic Methods, Freeze Frame Data for more information. Freeze Frame Data