Legacy ECU speaking CAN?

[pmcneill]

I've been browsing the service manual, and notice several mentions of CAN, the new protocol for OBD ports (or something to that effect). Does the 05 Legacy support CAN, or is that just internally, with the OBD port acting the same as previous models?

[Deer Killer]

The service manual says there is a high speed and low speed CAN bus. OBD II ports are supposed to have both busses wired to them, so you should be able to get access through that connector if your scanner supports it.

[pmcneill]

I was just pointed to [url]http://www.auterraweb.com/obdiipinout.html[/url], showing the pin-outs of the various different OBD interfaces. Comparing that with what's in the car (trying to see the connected pins), and, more importantly, the pinout listed in the Data Link Connector page of the Engine Diag section, it seems that CAN is only used internally. Good to know, I guess :)

[Deer Killer]

That's too bad if true however you can just tap into the lines wherever you want and either connect up the right pins on the obd connector or just use them as is into a scanner. I want to order an interface but I'm really waiting for someone else to confirm that brand X scan tool actually can talk to the bus...

[eamiller]

I did some research for a Toyota project I'm working on at work and came across these [url]http://www.emicros.com/[/url] . You can watch the messages fly by on the bus. However, good luck decoding the messages. Those are likely internal and unknown. Doubtful that any OBD scanner will decode the CAN messages properly.

[S4]

Would successfully tapping into the CAN network (and being able to read the messages) allow for us to have a tool like VAG-COM?

[Deer Killer]

[quote name='eamiller']I did some research for a Toyota project I'm working on at work and came across these [url]http://www.emicros.com/[/url] . You can watch the messages fly by on the bus. However, good luck decoding the messages. Those are likely internal and unknown. Doubtful that any OBD scanner will decode the CAN messages properly.[/quote] Yes, software will have to be written. Reverse engineering parameters should be (relatively) simple. There's already some open source stuff to do it, will probably just need to figure out what the various devices/registers are. Does that device have enough bandwidth to read both busses in real time? All the others seem to the can-serial-usb which means you can't capture everything.

[eamiller]

The USB device should be able to handle the 500kb high speed bus. I'm interested in these open source CAN Stuff you speak of..

[subieson26]

i have this scanner http://obdiiscanner.org/equus-obdii-scanner/equus-3030-innova-diagnostic-code-reader-for-obdii-vehicles/

 

i have used it once before to reset the CEL. i keep getting o2 error because of exhaust mods i've done. i went to use it again the other day after replacing my battery to reset CEL and it doesn't seem to be reading the scanner.

 

Anyone have any suggestions as to why? I have heard it might be a fuse, but other functions seem to be working fine (ie: car lighter, horn, interior light, etc.,)

 

thx

[farberio]

Yes, software will have to be written. Reverse engineering parameters should be (relatively) simple. There's already some open source stuff to do it, will probably just need to figure out what the various devices/registers are.

 

Does that device have enough bandwidth to read both busses in real time? All the others seem to the can-serial-usb which means you can't capture everything.

 

The theoretical limit for CAN is 1Mbps, USB should handle this but serial will not.

 

Reverse engineering the CAN messages gets tricky because the CAN messages are unique to the manufactures and then they change over time. And there are so many messages to parse through trying to find the message that corresponds to the action you are taking will be very challenging. And finding the CAN specs online have so far been elusive.