start procedure of a car in general?

Hi there. I am very new to Car Engineering World. basically i am a computer Programmer. I need to connect my Microcontroller (Arduino) to my Car and make a computer Software that can Start the Car (Start the Engine). Communication between the Microcontroller and Computer is not a problem for me, but the knowledge of connecting my Microcontroller to Car is very basic. Can anybody give me some detailed info on how the Car Starting (Car Self may be) is done? How the wires are connected to Battery and how it makes the engine start? Any diagram will be of great help.

It would be easier to help you if we knew the make and model of your car.   Your microcontrollers will need to be capable of providing a ground or 12 volt output at 200 milliamps.  You will need 2 or 3 outputs depending on the vehicle.  You will also need something capable of reading a pulsed DC voltae to let the computer know that the vehicle has started after the attempt to start.

I am planning to experiment on Nissan Avenir Salut X 1998-99 Model. I have a Arduino Board that is connected to PC and ofcourse i need to use the relays may be SSR from Arduino to CAR's SOMETHING to make it start but dont know what to know on the Car's side.

And a ground wire for neutral safety plus more outputs for lights, factory alarm control, oh wait a minute there's ready made product out there. As a rule household electricians and computer people make very very bad auto electricians. too many preconceived ideas and not enough prescience gained by experience.

howie ll wrote: As a rule household electricians and computer people make very very bad auto electricians. too many preconceived ideas and not enough prescience gained by experience.

I resent that remark... I am both a household electrician (USN Construction Electrician trained, thank you... all high (120V and up) AND low (120V and down) voltages) AND a "computer people"; I have my own relatively successful IT consulting business... MCSE in 2K and 2K3 Server, CompTIA A+ Cert, CCNA and CCNE studied (though never could afford the school, which comes with the cert...) Employed by Kern County, California as IT and microwave emergency radio installation, and rewired 22 library building's network infrastructures, both fiber and copper... Even with those perceived shortcomings, I am COMPLETELY comfortable and familiar with the functioning of automotive electrical and electronics. All true... "All generalizations are false."It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Phew! I thought a changing instantaneous voltage & current meant changing impedance. And a cap than can melt batteries but can't crank a car? (Even if those starter motors consume 40A or less!) Alas, some people just don't get it! (The humour that is!)

The typical start routine is:

Turn IGN relay and ACC relay on for a short time (1 second or so)

Turn ACC relay off while turning STARTER relay on

Monitor frequency of TACH IN signal - once frequency is above preset level for a brief time turn off STARTER relay and turn on ACC relay.

It would be nice to have a (-) status output turn on as soon as the sequence starts and turn off as soon as the system shuts off - this can be used to drive a security bypass (or for other reasons - they are just nice to have).  These are also known as GWR outputs (ground when running).

You'll have to incorporate some safeties in to the system, depending on what you are trying to do.  The safeties and security concerns are different if you are just trying to remote start the car verses trying to create a pushbutton start system.  For example - both systems should have a brake input, but on a remote start setup the brake input would shut the system down whereas in a pushbutton start system the system should not start unless the brake is pushed down.

Kevin Pierson

OK Haemphyst, I apologise to those like you who CAN do both but the exceptions tend to tend to prove the rule. I also get involved in Cat 5 wiring. At least I don't write rambling dissertations on bars with no catch line, your latest effort was much much better. And yes I know I just missed a great line at your expense on electricians not doing standup.