All vehicles built after 1992 had to be produced with lower emisions and used a Catalitic Convertor to do this. This ment that it was nececary for the control of the emissions needed to be much tighter and computor controled fuel injection and ignition systems were used to achieved this. These systems are great while they work properly but when they go wrong they can be quite dificult to diagnose the sorce of the problem. With so many different makes and models with often more than one suplier of a system for the same year and model of vehicle that causes quite a problem to keep up with the changes. In addition to engine related system there are ABS braking, Airbag, Dash related, Traction control, Emobolizer and other Secuity systems all can need checking at times. 
We choose Sun Snap/On as our suplier for diagnostic equipement. We updated software on a annualy basis on the first Scanner and are now on our 3rd machine. We now use there top of the range Modis scanner and osciloscope unit. This unit is great piece of equipement mainly dealing with european vehicles and covers most vehicles for engine, abs, airbag, and some dash related items. A lot of the security related systems are more difficult to deal with as information is dealer only. 
In addition we purchased a Sykes Pickervant Acr4 Code reader in an endeavour to fill some of the gaps we had in the european market. 
The Asian and Japanese vehicle in early years used a simple system of retreaving fault codes but as vehicle became more complicated they to needed specialist equipement to test their systems. To help us on this front we have a Hanatech multitester which has a very good coverage of the Asian Japaneese Austrailian American and some European vehicles. All of these above machines when conected to vehicle basicly talk to the on board computors and read any stored fault codes + live data in most cases. The problem with stored codes is you dont know how long ago the fault occured and the fault could be anywhere between the brain and the sensor or its earth. We conect a reader scanner to a car and on finding stored codes we then list faults, then clear codes and road test vehicle in the hope the problem reoccurs. Assuming code comes back wiring and sensors have to be tested with the apropriate equipement, multimeters lab scopes wiring break out boxes and sensor simulators are often needed to issolate the fault. Some problem reocurr regualy and so are easy to cure. Unfortunately often problems are quite dificult to find especialy those intermitent problems and to make things worse parts can be expensive and so every one is reluctant to order them unless you are sure it is going to cure the problem. One of the advantages we have over dealerships is we dont have to by manufactures parts and some times this can save you a considerable amount. There is not one make of equipement on the market which dose every vehicle well and it is imposible to buy every make of equipement. To help in those difficult problems we subscrible to three help line data services and have two specialist mobile companies who help on occasions as they have other makes of equipement which sometime do the job better on that vehicle. We are often booking work in 7 to10 days in advance but endeour to help on diagnostic problems quicker where posible. Please note electronic diagnosis is not an exact sience and isolating these problems can take more than a day so please dont expect it back before you leave it. | 