Quote:
Originally Posted by ballsdeep
Awesome build!
Been studying up on CAN bus and hope to learn from your setup. The A17 and D43 junction connections were used for your CAN1 and CAN2? Are the devices on CAN2 wired as a new main bus line from D43's 9 & 20 (lambda controllers as stubs, battery relay at the end), with a single terminating resistor?
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With the PDM CAN1 and CAN2 are completely different busses. On the CAN1 bus I am sharing the Motec and OEM signals. Luckily their CAN ID's don't have any overlap so it works out just fine. I tapped into the OEM bus at a junction behind the glovebox. Can't remember it's name off the top of my head but I believe that would be the D43 junction you are referring to. But from what I can tell in the wiring diagram the OBDII port is directly connected to the main bus without a buffer to block signals. You could potentially just connect directly to the port with the mating connector and save some hassle.
I have mine setup so that CAN2 is completely independent of anything that already existed on the vehicle. I have it reading all additional CAN based sensors and the keypad. On this bus I can send and receive any signals without any real worry of interfering with something on the main bus. Things like the AEM lambda controllers have fixed CAN ID's and formats so not all aftermarket CAN connections will play nice with the OEM bus (overlapping signal ID's). That is why I have them separated. That being said anything I read from CAN2 I can create my own ID and resend it to CAN1 with the ID, units, and scaling the Motec would expect, which is what I am doing for lambda and oil pressure signals.
My CAN bus knowledge is limited but from my experience it's best to minimize any additional signals sent on an existing critical bus if you can. Reading is one thing but sending signals can cause some unexpected problems. What hardware are you planning to add? @
geraldjust should be able to answer any CAN bus specific questions much better than I can.