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Single wire CAN vs two wire CAN

CANBus Communications Decoded

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Hello, I just watched CAN Bus Communications Decoded - Electrical Signalling. I actually signed up for this course because of the reverse engineering section, but the project I am working on is a 2004 Honda, which has a single wire CAN. For videos like this, any suggestions on reading material or otherwise where I can see the difference in what I am working with vs what the class is teaching would be great. If anyone can point me towards something where I can learn how the communications different between the two, it would be much appreciated.

Thank you

Are you sure what you have is CAN, and not K-Line or I2C or other single-wire protocol?

My current assumption is that it is single wire CAN, but it could be something else. Any ideas on how I can confirm without having the system online? The OBD 2 port only has a wire in the CAN high position, no CAN low.

What does the factory workshop manual and wiring diagrams indicate?

Also, be sure you are looking at the OBDII connector from the correct side. For example, from the incorrect side, the 3rd pin from the end is "vehicle/model specific" instead of CAN Hi. That's my guess -- it's some other diagnostic signal (could even be an RPM / tacho signal.

Here is an article that with some hints about looking at what pins are populated in the OBDII DLC connector to determine the protocol supported.

https://obdsolaris.com/obd2-technology-definite-interpretation/

Yeah, you'll need to confirm what protocol is actually being used. It could possibly be LIN, but the car is pretty old, so that does seem a bit unlikely.