Automobile DVD player can bus

Thread Starter

Smw

Joined Dec 25, 2016
9
Hello all, I’m working on a project at home.I have a really nice DVD player out of an suv, I have it all hooked up in my shop outside of the vehicle and it won’t power up. It has power and ground everything is hooked up just as it was in the auto. But it won’t play or light up the screen, it will load/eject dvd’s. The only hookup I cannot reproduce it the can bus + and - I believe this is a 5v communication line that all the modules in the vehicle “talk” on all at the same time of course and at different frequencies, also of course. I’m assuming that it needs this input to power up. I’m wondering if any of you fine people know a way around this or a way to replicate it and would be nice enough to share the information with me? Thank you in advance for any help you can offer.
 

bwilliams60

Joined Nov 18, 2012
1,282
Welcome to AAC. There are a lot of CAN bus articles on AAC so what you are experiencing is not uncommon. A lot of peripherals in vehicles now need signals brought in by the bus to awaken. You didnt't mention what type of vehicle but very likely your stereo needs CAN bus information to run. And possibly a security code. You can get information about the requirements from the OEM, car stereo installers or third party shop manuals. If you tell us year, make, model, we may be able to help you more.
on another note, CAN bus is not a 5V input. It is a communication bus that carries signals. Its voltage ranges from 1.5 to 3.5 volts depending on data coming across. There are some good YT videos on this subject. You can emulate the signals using a CAN sniffer. You can record a working unit and play it back to mimick the vehicle. Good luck on your adventure.
 

Papabravo

Joined Feb 24, 2006
13,456
Hello all, I’m working on a project at home.I have a really nice DVD player out of an suv, I have it all hooked up in my shop outside of the vehicle and it won’t power up. It has power and ground everything is hooked up just as it was in the auto. But it won’t play or light up the screen, it will load/eject dvd’s. The only hookup I cannot reproduce it the can bus + and - I believe this is a 5v communication line that all the modules in the vehicle “talk” on all at the same time of course and at different frequencies, also of course. I’m assuming that it needs this input to power up. I’m wondering if any of you fine people know a way around this or a way to replicate it and would be nice enough to share the information with me? Thank you in advance for any help you can offer.
It is a communication method used on vehicles. It is unlikely to be documented well enough for you to be able to use it outside the vehicle. The entertainment system is a primary attack vector for automotive systems which is why my friends at FCA tell me there is a relatively low order of probability that such information can be obtained easily. One method would be to purchase a CAN Network analyzer and use it to at least log and catalog the message traffic. Then you have to figure out which traffic is relevant to the device of interest. Then you have to figure out what the messages actually mean. It is a tall order and it might take you years of patient diligent sleuthing to suss it out.

EDIT: CAN systems generally require +5V and GND to power the transceiver in addition to a data pair which are labeled CAN_L and CAN_H. The signalling method is called Quasi-Differential with respect to a Common Ground. The Recessive level is CAN_L ≈ CAN_H ≈ 2.5V ≈ Vcc/2 where Vcc is the +5V used for powering the transceiver. The Dominant level is CAN_H - CAN_L ≥ 2.0V, which happens when CAN_H is actively pulled toward 5V (Vcc) and CAN_L is actively pulled toward GND. Power for the transceivers may or may not be isolated from all other power sources on the vehicle.
 
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MisterBill2

Joined Jan 23, 2018
5,741
You will probably discover that the player, if it is an OEM player, has an anti-theft function in the software so that if it can not communicate with some other module on that bus it will not function. I learned that the hard way after buying a used very nice radio-CD-cassette player from a scrap yard. And the car maker's dealer was no help at all in solving the problem. Evidently it is a one-time programmed code . Your efforts may be doomed, as mine were.
 

BobaMosfet

Joined Jul 1, 2009
1,056
Understanding & Using the Controller Area Network Communication Protocol
Author(s): Marco Di Natale; Halbo Zeng; Paolo Giusto; Arkadeb Ghosal
ISBN-13: 978-1461403135
ISBN-10: 1461403138
 

MisterBill2

Joined Jan 23, 2018
5,741
Understanding & Using the Controller Area Network Communication Protocol
Author(s): Marco Di Natale; Halbo Zeng; Paolo Giusto; Arkadeb Ghosal
ISBN-13: 978-1461403135
ISBN-10: 1461403138
Certainly handy publications but I really doubt that they will provide the correct pass-code to make the radio work.
 

bwilliams60

Joined Nov 18, 2012
1,282
Sometimes CAN bus modules can be back-doored by people in the knkw but you have to have the right tools, the knowledge and a little luck so that you do not brick the unit. Most people should not try this unless they fully understand what they are doing. As @Papabravo siad, it is a high security area of the vehicle and not easy to crack. Most modules can be read and written up to the advent of Global A vehicles. Before that they could be rewritten with proper equipment.
 

Thread Starter

Smw

Joined Dec 25, 2016
9
Hello all, I’m working on a project at home.I have a really nice DVD player out of an suv, I have it all hooked up in my shop outside of the vehicle and it won’t power up. It has power and ground everything is hooked up just as it was in the auto. But it won’t play or light up the screen, it will load/eject dvd’s. The only hookup I cannot reproduce it the can bus + and - I believe this is a 5v communication line that all the modules in the vehicle “talk” on all at the same time of course and at different frequencies, also of course. I’m assuming that it needs this input to power up. I’m wondering if any of you fine people know a way around this or a way to replicate it and would be nice enough to share the information with me? Thank you in advance for any help you can offer.
 

Thread Starter

Smw

Joined Dec 25, 2016
9
Hello all, I’m working on a project at home.I have a really nice DVD player out of an suv, I have it all hooked up in my shop outside of the vehicle and it won’t power up. It has power and ground everything is hooked up just as it was in the auto. But it won’t play or light up the screen, it will load/eject dvd’s. The only hookup I cannot reproduce it the can bus + and - I believe this is a 5v communication line that all the modules in the vehicle “talk” on all at the same time of course and at different frequencies, also of course. I’m assuming that it needs this input to power up. I’m wondering if any of you fine people know a way around this or a way to replicate it and would be nice enough to share the information with me? Thank you in advance for any help you can offer.
 

Thread Starter

Smw

Joined Dec 25, 2016
9
It’s an 06 Pontiac Montana sv6. Boy I hate to waste it it’s a very nice self contained ceiling mount unit. And to clear any small doubts if any it’s not stolen I work for a towing company and it was an unclaimed vehicle. I have a two piece unit(s) from an 04 Durango same deal won’t power up. I very greatly appreciate all of your replies, you folks are very knowledgeable and the candle I hold next to you just got dimmer. Lol. The fellow that mentioned the CD player I ran into a similar situation. My CD player in my am, fm, tape cd quit every thing else worked it bugged me enough to get one from a salvage yard 100.00. I put it in and nothing after thinking and calling to confirm for theft reasons they are vin specific the dealer wanted another 100.00 to make them match I really like the player it sounds very clear and crisp best factory setup I’ve seen. So me trying to keep a bad situation from getting worse I took the two apart and just swapped the cd drive (very simple) put it all back and three years later still good but staying away from sketchy unknown homeburnt cds. Once again thank you all for the very wise info
 

Papabravo

Joined Feb 24, 2006
13,456
I think we all believe you that the unit was appropriately salvaged. What we are trying to tell you is that the automobile manufacturers are actively working to prevent you from trying to do what you want to do by a variety of means. This includes, but is not limited to, restricting access to documentation and information, conditioning proper function of the unit on access to other vehicle components, and the use of security protocols to prevent the unit from functioning as a standalone device. We are not, repeat not, trying to suggest that you are trying to do something untoward.
 

Thread Starter

Smw

Joined Dec 25, 2016
9
I think we all believe you that the unit was appropriately salvaged. What we are trying to tell you is that the automobile manufacturers are actively working to prevent you from trying to do what you want to do by a variety of means. This includes, but is not limited to, restricting access to documentation and information, conditioning proper function of the unit on access to other vehicle components, and the use of security protocols to prevent the unit from functioning as a standalone device. We are not, repeat not, trying to suggest that you are trying to do something untoward.
I appreciate that I didn’t think anyone did but never hurts to clear the air. I’m sure they want to be the ones to make money off of THEIR property I can’t really blame them but what a waste if there isn’t some way to repurpose even as just a monitor for another DVD player. Thanks again, Steve.
 

Papabravo

Joined Feb 24, 2006
13,456
I appreciate that I didn’t think anyone did but never hurts to clear the air. I’m sure they want to be the ones to make money off of THEIR property I can’t really blame them but what a waste if there isn’t some way to repurpose even as just a monitor for another DVD player. Thanks again, Steve.
We were born in a bygone era where things could be repaired and re-purposed without anybody thinking twice about it. Pity the poor farmers who pay $200,000.00 plus for a piece of machinery that they are forbidden by law from repairing or upgrading without the permission of the Almighty John Deere. Talk about an ass-raping going on there.
 
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Thread Starter

Smw

Joined Dec 25, 2016
9
We

Were born in a bygone era where things could be repaired and re-purposed without anybody thinking twice about it. Pity the poor farmers who pay $200,000.00 plus for a piece of machinery that they are forbidden by law from repairing or upgrading without the permission of the Almighty John Deere. Talk about an ass-raping going on there.
Yes that sounds like someone wanting full control over things. I hadn’t heard that before. Sad if “you” buy something it’s not really yours free and clear, but we should be used to it such is land and earned money taxed coming and going. I understand the need for reasonable tax if spent correctly but damn. Ok better stop on political bs lol
 

MisterBill2

Joined Jan 23, 2018
5,741
I think we all believe you that the unit was appropriately salvaged. What we are trying to tell you is that the automobile manufacturers are actively working to prevent you from trying to do what you want to do by a variety of means. This includes, but is not limited to, restricting access to documentation and information, conditioning proper function of the unit on access to other vehicle components, and the use of security protocols to prevent the unit from functioning as a standalone device. We are not, repeat not, trying to suggest that you are trying to do something untoward.
Exactly what I was trying to get across in my first post. The feature was, and still is, primarily for the purpose of eliminating the value of stolen car entertainment equipment. That problem was epidemic in my area at the time. Removing the radio took about 15 seconds without any real tools, and so even in new car lots they were being ripped off.
The one thing that might work would be to get ALL the smart devices from a wreck and change over the system. But if a dealer can fix it that means that it is possible, so keep on looking.
 

BobaMosfet

Joined Jul 1, 2009
1,056
Certainly handy publications but I really doubt that they will provide the correct pass-code to make the radio work.
No, but it's a starting point to understand the protocol and the bus. The passcode isn't hard to figure out, but you need to understand the protocol and be able to watch the bus. OEM mnemonics for CAN are usually proprietary, and found in documents they closely guard, but there are ways around that if you know what you're doing. Anyone fiddling with their CAN bus should make themselves are of the local ordinances- some principalities make it illegal to do so.
 

BobaMosfet

Joined Jul 1, 2009
1,056
We were born in a bygone era where things could be repaired and re-purposed without anybody thinking twice about it. Pity the poor farmers who pay $200,000.00 plus for a piece of machinery that they are forbidden by law from repairing or upgrading without the permission of the Almighty John Deere. Talk about an ass-raping going on there.
It's true times have changed. Sadly, the reason such changes exist isn't because of the OEM, it's because of STUPID USERS. People who have not the brains nor skill to correctly and accurately make such repairs without potentially making the device/tool/equipment dangerous to themselves and others. If those incompetent ones that did this would also accept their responsibility when they get maimed, hurt, injured, killed or cause the same for someone else, the OEM wouldn't have to put such things in place, because they wouldn't be afraid of being sued by fools.
 

MisterBill2

Joined Jan 23, 2018
5,741
It's true times have changed. Sadly, the reason such changes exist isn't because of the OEM, it's because of STUPID USERS. People who have not the brains nor skill to correctly and accurately make such repairs without potentially making the device/tool/equipment dangerous to themselves and others. If those incompetent ones that did this would also accept their responsibility when they get maimed, hurt, injured, killed or cause the same for someone else, the OEM wouldn't have to put such things in place, because they wouldn't be afraid of being sued by fools.
OK, I have heard that story about stupid modifications and it smells a bit like week old shrimp heads in a garbage can. It is mostly about profit and keeping any aftermarket folks out of the business. The situation is very similar to that with cell phone charging cords, and computer power supplies, a while back. Every phoe and every computer would only work right with that horribly expensive OEM power device. The claim is that it was for safety, the reality is that it was for profit. If DigiKey can sell the supply for $20 and make lots of money then why does the similar supply cost $110 from the OEM?? It was all about profit, folks. It was never about safety.
 

narkeleptk

Joined Mar 11, 2019
435
I rarely fool with bench testing radio's but you shouldn't need the can lines connected for GM radio's of this year to power on. These radio's are very basic. However they do preform a vin verification or it will be locked. Still you should see "LOCKED" on the display. I bet your just missing one or more of the "ACC/RUN" wires if you do not see this. I'm not sure which module they verify with, probably just the BCM in which case you can manually edit the VIN to eeprom from a used bcm (or use the original bcm from same car if available) and hook up both bcm+radio and it would work.

Another thing you can try that works on many GM radio's is to open it up and look for a soic8 eeprom usually of the 93CXX or 24CXX family and remove it. Doing this bypasses the verification check. It will toss some error's at first start but after it should start to function like normal.
 
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