Any one please help me to interface arduino to the car's ECU for tracking the speed RPM etc...There are some posts about this topic here but none of them gave a complete detail. 
check these links
Practical Arduino: Cool Projects for Open Source Hardware (Technology in Action)
This excellent book has a guide showing how to do this.
thank you 
If your car has CAN-BUS then there is a shield for this:
http://www.skpang.co.uk/catalog/product_info.php?cPath=140_142&products_id=706
YouTube Video
Hello,
I'm working on similar project. I used, ELM327 based Bluetooth and USB modules.. This combination makes life extremely easy (most of the protocol/signal dependent issues are being handled by ELM327) ..
If you prefer to do this way.. I can give you more information on this. (where I buy modules, how to start etc)
if you check
you can find which code to send to EC ( 01 0C in fact)
regards, reha
Hi I am a newbie. Have played with Arduino a bit, and have got some questions regarding OBDII if anyone can help. I live in South-Africa and I drive an Isuzu KB220 LE (2.2 Litre Petrol(Gasoline) 2000 Year Model). I have had some problems lately with the ECU and Check engine light. I have had the ECU repaired, but still getting the MIL light come on. Auto Electrician cannot sort this out.
I am now planning to build my own Arduino / OBDII Interface so that I can read the fault codes etc. My first problem is that I need to identify the OBDII protocol. Now it seems that Isuzu (GM) is all J1850 VPW as far as I could get from the Internet. However as I said I am in South-Africa and not sure what protocol they would have implemented in this vehicle. Can Anybody help me PLEASE ?? This is what I see in the vehicle: (see BMP of OBDII Connector) How do I paste a Bitmap from my Computer ??