I am planning to upgrade our car fleet at home with hopes to secure new contract in IT/IS space good enough to buy couple of 2007 Toyotas :-)

While siting at home - contract hunting - I've put a lot of time in research about new Toyota models - both mechanics and electronics as I am electronic engineer.

New cars are becoming more and more computerized with multiple computers controlling Engine, Transmission, ABS,TRC, VSC, Climate Control system with Aircon, Airbags (SRS), even tyre pressure and brake pads thickness in some models.
And cars have On Board Diagnostic System (after 1996/1998 -> OBD-II). 
I was familiar with OBD-I for Toyota and aware of 101 trouble codes for Engine, ABS, Transmission and SRS) but OBD-II is more complex.
OBD-It saved me a lot when I was buying my current car at the auction as one of 3 I wanted were faulty.

Mechanical checks which are offered at car auctions and car markets do not offer computer scanning and not good enough for me. One mechanic even told me "if Engine Light is not on - I would not be bothered" - pathetic ignorance and customer misleading - he charges $140! I hope he is good at what he is checking mechanically.

Service stations charge from 60 to 120 and more just for reading OBD-II trouble codes but they would not let expensive scanner outside the workshop (i.e. when buying at auction).

I made a thorough research in regards to OBD-II and found out:

- generic cheap OBD-II scanners one can find online are complete waste of money as those are normally for US market. Different car manufacturer's protocols are different. Proprietary scanners are for particular makes - e.g. what is good for Jag will not work with Toyota. Different scanners should be used for Honda, Holden, Mitsubishi etc. Cars made for different markets (Europe, Japan, USA) may require  different scanners.
- cars made for Japan Domestic Market will NOT put the engine light on if for example oxygen sensor is dead (in my case - found it with diagnostic knowledge I've obtained and changed the sensor myself - less fuel consumption now)
- the Check Engine Light was not "on" when ABS brakes system was down on my friend's car - brakes just worked as if ABS were not there. ABS light was not on for some reason as well but trouble code suggested faulty ABS sensor. 
- with a proper scan tool on some makes/models you can read the real odometer (some buggers reprogram odometer chip so the car looks fresher but engine computer actually may keep the real mileage or the record about last time the trouble codes were erased - maximum 65535 km). My friends from BMW forum in Moscow reported a lot of cases they found the case. 
- you can be you own mechanic and run tests for different systems in your car to save on diagnostics fees
- as a result I've purchased with trial and error few scan tools and now I can read Toyota/Nissan multiple parameters (hundreds) on a dealership level, read proprietary codes - intermittent, historic and active, run tests, erase codes etc.
Happy and feel safe when I will go to buy that new dream car. It may also read some info from Mitsubishi, Honda, Hyundai - but I did not tried yet.

Practiced on my friend's and neighbors Toyota cars.
 
My neighbor who was very pleased with the results that his $19K Toyota is free from faults said I should stop looking for IT/IS job (for the last 5 years I was in change, release and compliance in NZ) and start my own business. 

- What anyone think about doing "electronic health check" of their own car or when you go to buy the new second hand one (as a supplementary to mechanic checks)? 
- Or it is easier not to think about it and deal with the problem when it happens - visiting service station when it brakes and let them fix it?
- What would be fare price for it?