CarCoder

Hello guys,

I'm kinda new here so please don't be surprised if I ask something stupid.

Anyway, I want to send commands to my car like turning off the engine, lock the doors, close the windows etc...

I like to know the commands and I don't know if these commands are included in the OBD protocol. Cause isnt't that OBD is more for analyzing purposes instead of controlling the whole carsystem?

So my goal is using CAN to connect my microcontroller on it and send commands (using or not the OBD protocol) to control the car. With controlling the car I mean by controlling the doors, windows and turn on/off engine, lights etc... (ofcourse not controlling fuel injection system and other engine related stuff, or whatever critical systems).

Another important thing is that it should working for most different cars (I know there are differences and some functions are hidden etc...).

Thank you very much.

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Sonicxtacy02

the obd options that i know of only READ data and dont have the capability to write it.

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CarCoder

Thnx for reply,

But does someone knows some links, articles explaining how to control as mentioned in my previous post.

Grrrmachine

I suppose if you wanted help it might be advantageous to mention what car you have, as stuff like ignition and windows is proprietory for the marque, rather than standard for all modern vehicles.

My one doesnt even have fuel injection, so I can't help you on the specifics

CarCoder

Well I guess the only way to get the info is to reverse-engineer on the CAN bus.
That's a nice challenge for me too. But first I need to write some tools to get things done. Anyway, if I have some info you'll get it as soon as I get finished doing some reverse-engineering.

bbalazs

Trying to do the similar thing on my car, I recognised, the OBD is just for MONITORING certain parameters that closely linked to the environmental pollution. Not useful to you.

BUT

Via the same connector, you are able to talk to ECUs.
These ECUs are different computers and control certain sub-functions of entire car (e.g. airbag, dash, ABS, climatisation, engine, etc.). They are also continuously communicating with each other.
The communication method they use can be e.g. CAN or ISO or PWM, etc.
They have company-specific protocol (series of hexadecimal numbers). And via these protocols, you are able to control ANY function of that ECU (maybe just after an authorisation process).
In my case, luckily, have a program DDT2000, that contains all the possible commands to any ECU.

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HisSketchiness

You could try looking into a fusion brain. It's separate from the cars systems but allows computer and/or sensor inputs and can send outputs to relays to do whatever you want.

dopey273

There's a couple of different parts you can get to make this happen. I"m going to assume you have a chrysler product since you said can bus. There are modules made to interface with the can bus system That will lock/unlock the doors and interface with the the car to help start it. You will still need something to send the basic commands to control the modules(which what I've seen here shouldn't be to hard). Basicly these parts are used to interface security/remotestart systems to the cars. If you look at www.xpressdownload.com or www.idatalink.ca .you basicly have to send a negative pulse to work the module. Hope this helps you in your system design.

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The1Architect

this is what you need

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CarCoder

Thanks for your response guys,

In my project I can't use external modules, the situation is as follows. I build in a remote system which can talk on the CAN bus. So it's like a pc connecting to a network. Than send the right predefined messages to control the doors, windows, lights and switching on/off the engine.

txspazz

Clifford’s http://www.clifford.com/ G4 and G5 AvantGuard series alarms can control everything you are looking for using a serial connection. Not sure if that is what you are wanting or not wanting when you say you can't use external modules.

To answer your original question, my experience is limited to Fords, but using there hand held diagnostic scanner (NGS) you can control many of the types of things you are wanting (things controlled by the BCM and some things controlled by the PCM). This isn't using OBD protocol, but does use the same port.

chewwtoy

The simple answer is you need to connect to the vehicle's CAN network. But not all vehicles are the same. And many of them have more than one CAN network. So depending on the car and the things you want to control, the hardware and software will be different.

Nearly all vehicle that support CAN networks, support what is called ISO 11898 this is the dual wire high speed can on the OBDII port pins 6 and 14. To connect to this network you need a hardware interface that supports MORE than diagnostics. So these ELM and ELM-like devices will not do. You need a device like the Mongoose or the ValueCAN (google them for more info). These device support real-time monitoring of ECU to ECU traffic (not the same as diagnostics). The ValueCAN can connect to this network but you'll also need software, at the same site you should find a downloads section then there is a software application called CANcracker (or something like that). This is a free application that helps to reverse-engineer the CAN network.

But be aware that many vehicles don't use the network on PIN 6 and 14 but some on PINs 3 and 11 or PINs 1 and 8 or in the case of GM vehicles PIN 1 has a single wire CAN which is different and doesn't work with the ValueCAN.... I'm not sure about the Mongoose.

It takes a lot of patience but it can be done.

Oh and one more thing the vehicle has to support controlling things via the CAN bus .. just because you connect to it, doesn't mean that you can control it via the network.

Good luck

Lukeyson

The ELM is still capable of doing most of what the Mongoose can do - just not as fast, without as much control over the frame formatting and timing, and only one protocol at a time. But I have certainly been able to do some programming of non PCM modules without problems on an ELM. But sniffing at full CAN bitrate is another problem altogether.

(a) There are no standards to do what you suggest. The only standards that manufacturers conform to are J1979 and in some cases J2190. These can only do read operations from the PCM for Emissions.

(b) Some cars can do what you require, and some cannot. Each implementation is different, prioprietary, and not public knowledge. The kinds of things that are configurable or programmable across the Bus are there so that Technicians can use Manufacturer tools to adjust these values in the workshop.

You can get Manuafacturer specific stuff if you are a member of ETI. But it's not cheap. Another option you have is to license Prioritary codes from the manufacturers if you plan to sell a software tool.

One path I have followed is to access a manufacturer diagnostic tool, and use tools like the ELM or Mongoose to 'sniff' the traffic between the car and the diagnostic tool as various different tasks are performed. This is very easy on the CAN bus using an OBD2 'Y' Cable. But it takes a lot of time and dedication to get what you want - and access to the tool in the first place. Suffice to say that manufacturer workshops won't just let you walk in off the street and let you do this.

If it were easy and cheap, there'd be lots of easy cheap software tools out there by now. The only easy cheap stuff out there is pretty much just J1979. Anything beyond that is the reason why these tools cost so much money.


Lukeyson

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