Effective Diagnostic Techniques

WARNING: This page is about a different car, the 2013 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

The following diagnostic process is critical for consistently successful diagnoses. Random methods work inconsistently and often lead to multiple repairs and the accompanying frustration.

Understand and verify the symptom .
- Understanding a symptom requires understanding normal operation.
- Duplicate the concern. Re-create the same conditions that demonstrated the original concern (road testing may be necessary).
Determine the responsible system .
- Gather data, such as a visual inspection and an OASIS report.
- Perform system tests, such as pressure tests or DTC retrieval.
Identify the responsible component .
- Test the suspect component and related parts.
Determine the root cause
- Examine related components (wiring faults, misalignments, incorrect adjustments) that may be the actual cause or may have caused the component failure.
- Repair all related faults to avoid repeat failures.
- Verify the repair has corrected the concern (and not created any new ones) using the identical conditions that demonstrated the original concern.