Manipulating things in a car

Ideas and discussion of what to do with the CAN Bus ( i.e. XMDirect, iPod, Carputer, etc... )
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Suncar
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Joined: 2016 Mar 04 07:10

Manipulating things in a car

Post by Suncar » 2016 Mar 04 08:20

Hey guys

Im currently working on a student project in which we transform a normal BMW X5 to an electrical vehicle. At this moment we took out all the unnecessary components and put in the electric motors, a large battery from a Tesla Model S etc etc... (the car is running).
Of course we have to do some interaction with components that were already in the car like the gas pedal etc by can which seems not to be a problem as long as we only need to read from the can bus. But right now we try to manipulate some things in the car by sending messages to the can bus which seems to be not that easy. Our main concernt at the moment are all the error messages that are lit up on the dashboard because of all the missing parts. We imagine that it should be possible to kind of simulate the missing parts by sending their can messages with our controller to the car so that the car thinks everything is as it should be.
To test this we looked for a simple thing with visual feedback if our idea works. We proceeded to look for the signals that open and close the windows of the car and tried to send those messages with a computer to the can network but nothing seems to happen.
We work with PCAN explorer to read and send messages and we also have the whole can message catalogue from BMW for the car.

Can it be that simple or are we making a bigger mistake here? Is it maybe not possible just to send those messages to the can bus because they are always overwritten by the ones from the car's ECU?

We already read some of the threads in here where people state that they are able to open and close windows step by step and I think this should be able in our car too. So if someone that has done that could help it would be really great!

For any hint we are more than thankful :)

Greetings from Switzerland

robertoal
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Joined: 2016 Feb 26 10:12

Re: Manipulating things in a car

Post by robertoal » 2016 Mar 06 12:48

First of all.. Great project!
Second. All my knowledge is from the big Internet and haven't played around much in real world, but some ideas I come up with are:
1. If there are nodes which the car expects to be present you can capture all the data from those nodes using Linux. Do hook up the node of which you think are necessary for correct operation, record all the messages and replay them in the car. This way you emulate the node so the car thinks it's present.
2. Can bus works with arbitration. The lower the value of a node ID the higher it's importance is. If you Google Texas instruments canbus basics you find an PDF stating this.
3. Why use the ECU? Abs node I can understand but ECU.. Is this really necessary?

Just my two cents, would love to learn from your project!

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