- Noise is defined as sounds not related to the normal operation of the cabin equipment that affect the customer's satisfaction with the ride.
- Vibration is defined as impulses/tremors felt by the customer that are independent of the road surface.
- Rigidity is a type of vehicle movement that allows the customer to clearly perceive the vehicle's response to the quality of the road surface.
Theory of diagnostics
Diagnostics is more than following a precise series of interrelated steps to find the cause of a particular problematic condition. It is a way of observing systems that are not functioning properly and determining why. It is also about understanding how the system should work and whether it is working properly.
There are basic rules for conducting diagnostics. If you follow these rules, you can usually find the cause of a particular problematic condition the first time you examine the system.
Knowledge of the system
- Knowing how elements fit together/interact with each other.
- Knowing how a system works, as well as knowing its limiting characteristics/states and what will happen if the system does not operate properly.
- Sometimes this means testing a system against another system that is known to work correctly.
Knowing the history of the system
Knowing any of the following can save time:
- How old or, conversely, how new is this system?
- What repairs were carried out?
- Has any maintenance/repairs been performed in the past that could have led to the current condition?
- What is the system's service history?
Knowing the history of the condition
- Did the problem occur suddenly or did it develop gradually?
- Was the problem related to some other events, such as a collision or a previously performed element replacement?
- Knowing how the problem became known; this can be an important "clue" when searching for the cause of the malfunction.
Knowing the likelihood of developing certain conditions
- A simple cause is more likely than a complex one.
- For example: Electrical problems usually occur in connections/connectors, not in components; The failure to start the engine is most likely caused by a broken wire or a small misalignment, and not a broken camshaft.
- Knowing the difference between the impossible and the improbable. Certain failures/malfunctions in the system may be improbable, but they still happen.
- New elements are just new elements. This does not mean that they are always well-functioning elements.
Eliminating the symptom of a malfunction but leaving the cause
Reducing the front tire pressure may eliminate the vehicle pulling to one side, but will not correct the underlying cause of the problem.
Confidence in the found cause of the malfunction
- Double check
- What caused the element to wear out?
- A loose transmission or engine mount may indicate that other mounts are also loose.
Diagnostic tables
Tables are the simplest way to express the relationship between the main logical and physical elements of a system. Tables help to find the cause of a problematic condition in the shortest possible time. Diagnostic tables combine many diagnostic zones into one "video sequence" showing:
- the probability of certain phenomena occurring in a system
- the speed of checking certain elements and functions compared to others
- the ease of performing certain tests compared to others
- eliminate the need to check large parts of the system by performing simple checks
- narrowing the search area to a small "point" before performing a deep scan
The fastest way to identify the cause of a problematic condition is to work with the available instruments and tools. This means working in accordance with diagnostic tables using the appropriate special equipment.
There are a number of testers suitable for use on Ford vehicles that are used to diagnose NVH problems. They are designed to detect mechanical noise, wind noise, and squeak and rattle type noises.
The equipment is supplied under the FSE/Rotunda program.
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