Guys, I am also one of the proverbial six blind men who is feeling up this elephant called on-board diagnostics, particularly in Indian context.
Indian cars are very lax from the OBD compliance perspective, but lately a lot of cars, particularly from GM etc are having the OBD-II port. One reason is maybe the cars are now being introduced globally and therefore have very little differences in them - For example, Honda City in India and South East is also marketed as Honda Fit Aria - Its exactly the same vehicle, with a different name.
In these circumstances, it is often too inconvenient for the manufacturers to strip every small detail of the vehicle which is statutorily not required. So they let that feature be, and may be hype it wrt competition, as it offers a certain functionality.
OBD has also undergone transitions, appearing first as some an ancient protocol called J1850. Then on, in the 1990's, the protocol changed to ISO9141 and then ISO9141-2. My Honda City supports ISO9141-2 protocol, which has a 1-wire, half duplex asynchronous communication interface. The latest interface being used for OBD is CANbus, on which the entire world seems to be converging. All modern vehicles use the 16 pin standardized DLC (data link connector), commonly described on various websites.
The information available on OBD is often sketchy, and because of the tendency of the auto mfrs. to keep their electrical diagrams and service manuals confidential, nothing of consequence is available in public domain. So one has to rely on word of mouth or unsubstantiated data. Going to your authorized service station and requesting (for a long time) to be shown the electrical diagrams of the vehicle would help too.
Hopefully this info is useful to you, for the Santro specific query, I hope someone will respond.
|
