Vida CEM swapping

[andrewgabler]

Forgot to mention in my post that the canbus shield has a 120ohm switch and I have tried with and without it enabled

[xanthefin]

In CAN there is two on each end (120 Ohms) so 60 Ohms when measured in "middle" when both ends are connected. I didn't check was your pins correct though but my 2 cents.. i use oscilloscope when something wrong.

[rkam]

I have tried a number of different combinations of things.
SETUP
PIN 6 12v Ground
PIN 8 +12v
PIN 15 + 12v
PIN 16 + 12v
PIN 33 CAN Hs - H
PIN 48 CAN Hs - L
PIN 40 CAN Ls - H
PIN 55 CAN Ls - L

What am I missing to get the canbus network to wake up and at least be read from my canbus shield? Thanks!

Try to add +12V to D60 and the two large terminals near the fuses on the other side.

[andrewgabler]

That does not work either… with any of the 4 CEMS I have.

[xanthefin]

I have stupid question about your set up but i focus like how i would personally try so can sound as such next thing...
Do you try connect CEM on to CAN Bus via OBDII port or you bypass OBDII port side of the CEM?

On car you need "wake up" OBDII port CAN Bus before communicating it due micro relays in CEM being closed.

P.S. I have no this teensie thingy project or tried it.. so i am not speaking directly and mostly what you maybe aiming for so i might speak side of your project. I just use Arduino's much lower spec devices.

[andrewgabler]

I’m not sure fully what you mean by bypass the obd2 port? I have tried a number of the canbus pins on the CEM. Currently I am just trying to get this to work with my arduino as well.

[vtl]

Do you get any messages on the bus if you just listen the bus passively and power the CEM on? It normally shoots a bunch of messages and then falls asleep.

[andrewgabler]

That’s basically what i’ve been attempting to do, the power draw and voltage across the can bus lines tells me it’s doing something like that, but it’s not coming up on my logger

[dikidera]

It pays off to step away from RE for a few weeks. I can't believe I didn't think about this 2-3 months ago.

ECM communicates via CAN to TCM. I just had to see where the ECU updates TCM related variables. From there it is apparent which functions are related to CAN send/receive. Obfuscation is in the way, but this doesn't matter. And it is all related to FFFF7448.

Then I also had a theory, that any of these modules must send the data at least several times per second to ensure it is received.

Anyway, there are several receive and send CAN functions, each for the size of the payload. Byte,Word,DWORD.

[vtl]

That’s basically what i’ve been attempting to do, the power draw and voltage across the can bus lines tells me it’s doing something like that, but it’s not coming up on my logger

CEM draws around .12-.14A while awake (cracking pin) and .08 when sleeps.