Advanced Automotive Fault Diagnosis
tải về 7.07 Mb. Chế độ xem pdf
|
LÔØI NOÙI ÑAÀU, ledklok
- Điều hướng trang này:
- 2.4 Mechanical diagnostic techniques 2.4.1 Check the obvious first!
| 2.3.3 How long is a piece of
string? Yes I know, twice the distance from the middle to one end! What I am really getting at here though is the issue about what is a valid reading/ measurement and what is not – when compared to data. For example if the ‘data book’ says the resistance of the component should be between 60 and 90 ⍀, what do you do when the measured value is 55 ⍀? If the measured value was 0 ⍀ or 1000 ⍀ then the answer is easy – the component is faulty! However, when the value is very close you have to make a decision. In this case (55 ⍀) it is very likely that the component is serviceable. The decision over this type of issue is difficult and must in many cases be based on experience. As a general guide however, I would suggest that if the reading is in the right ‘order of magnitude’, then the component has a good chance of being OK. By this I mean that if the value falls within the correct range of 1s, 10s, 100s or 1000s etc. then it is probably good. Do notice that I have ensured that words or phrases such as ‘probably’, ‘good chance’ and ‘very likely’ have been used here! This is not just to make sure I have a get out clause; it is also to illustrate that diagnostic work can involve ‘playing the best odds’ – as long as this is within a logical process. 2.4 Mechanical diagnostic techniques 2.4.1 Check the obvious first! Start all hands on diagnostic routines with ‘hand and eye checks’. In other words look over the vehicle for obvious faults. For example, if auto- matic transmission fluid is leaking on to the floor then put this right before carrying out complicated stall tests. Here are some further suggestions that will at some point save you a lot of time. ● If the engine is blowing blue smoke out of the exhaust – consider the worth of tracing the cause of a tapping noise in the engine! ● When an engine will not start – check that there is fuel in the tank! tải về 7.07 Mb. Chia sẻ với bạn bè của bạn:
|