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Discussion Starter #1
I have been working on a project which would interact with the canbus, however instead of risking my own car and ecu I was going to buy one off eBay and power it with a standard desktop power supply.

However most of them don't come with cables and I really don't want to borrow them from my car. Does anyone know which cables I would need to plug into the back of the ECU or at least have a schematic for the pins?
 

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I think the cables is only the start of it. Once you have the cables, you'll discover that it will want to talk to the rest of the modules.

If you've got the space, I'd suggest buying a wreck. That way you have the whole system. If you want, you could probably extract what you need and once you know you have everything sell the rest for scrap and come out about even. But I have a feeling that you're going to find that the computer will want to "see" the rest of the car. Hood/Doors/Trunk open or closed? etc.
 

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I first want to start building a stable circuit where I am able to sniff the network to make sure I can properly read the packets first. Then I wanted to record and analyze the data to see if I send it back across the ecu successfully. Ideally buying a wreck would be nice because then I could experiment with some other devices but unfortunately I do not have the funds for that at the moment. But I first need to find some cables that will work so I can attach the CAN signals to my custom circuit. Another options would be to listen from the obd2 port but that is for diagnostics, so you can't do any of the 'fun' stuff and would need to access to the CAN anyways either from the radio or ECU. Anyways, I have been trying to find some schematics, but turned up short. However, going with what you said, if I go to a junkyard maybe I could pull the wiring harnesses along with the ecu with it.
 

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You can get some schematics if you lay out the $200 for the Helm service manual. I say "some" because all they show you is from the harness level - nothing inside the magic black boxes.

if I go to a junkyard maybe I could pull the wiring harnesses along with the ecu with it.
Sounds like a plan.
 

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I first want to start building a stable circuit where I am able to sniff the network to make sure I can properly read the packets first. Then I wanted to record and analyze the data to see if I send it back across the ecu successfully. Ideally buying a wreck would be nice because then I could experiment with some other devices but unfortunately I do not have the funds for that at the moment. But I first need to find some cables that will work so I can attach the CAN signals to my custom circuit. Another options would be to listen from the obd2 port but that is for diagnostics, so you can't do any of the 'fun' stuff and would need to access to the CAN anyways either from the radio or ECU. Anyways, I have been trying to find some schematics, but turned up short. However, going with what you said, if I go to a junkyard maybe I could pull the wiring harnesses along with the ecu with it.
Both high and low speed busses are available at the diagnostic port and you should be able to sniff all data there, your problem is going to be breaking into the encrypted protection scheme GM has used on some of the modules to do anything to the firmware routines which I assume is what your wanting to do, not impossible and has been done by the tuners on the ECM module, the micros will have a back door, identifying the micros will also be tough since I'm sure GM has them house numbered
 

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The same place that will sell you a pcm can probably get you the harness since 99% of the time its a salvage yard that is parting out the car
 

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Both high and low speed busses are available at the diagnostic port and you should be able to sniff all data there, your problem is going to be breaking into the encrypted protection scheme GM has used on some of the modules to do anything to the firmware routines which I assume is what your wanting to do, not impossible and has been done by the tuners on the ECM module, the micros will have a back door, identifying the micros will also be tough since I'm sure GM has them house numbered
You are absolutely right, though you may be able to piggyback off of the firmware that is already written by Remote start bypass manufacturers :) I bet their encryption is less than 80 bit.
 
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