Effective Diagnostic Techniques
WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Do not use this document in place of Ford-prescribed Symptom Based Diagnostics or Service Information diagnostics. Diagnostic Methods is intended to provide Ford vehicle diagnostic information only for support of Ford-prescribed diagnostics.
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. Recreate the same conditions that demonstrated the original concern (road testing may be necessary).
- Determine the responsible system
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- 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
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- 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.