SWCAN Wakeup Issue

Hey guys - I just go a M2 this week and have been playing around with it on my vehicle - I have a 2014 Silverado and a 2019 Traverse.

My goal is to setup a M2 in each with a Digi LTE modem paired with a custom app to run remote start, and door locks. Maybe do GPS tracking eventually as well.

I am fairly new to the Macchina World (obviously) but not new to CANBUS. I have been developing CANBUS modules in the Ag Industry for a while. Its pretty similar, but this is my first project with SWCAN.

Anyway…I’ve got my module reading message with no issues, and I’ve determined what frames I need to replicate from the OnStar Module to run my commands (both vehicles have an active subscription right now for testing). The frames I came up with are the same as other have posted, so that a good sign.

I have started just trying to wake the vehicle up, but can’t get that to work even.

The 2 frames that my silverado seems to be sending are the 0x100 wake up, and 0x62D with data {0x01,0x40,0x00,0x00,0x00,0x00,0x00,0x00}

My flow is this, and I’ve changed it up a few different ways with no luck.

  1. change Mode to 2
  2. wait 200ms
  3. Send 0x100 wake up (tried this with len = 8 with all 0’s and with len = 0)
  4. wait 200ms
  5. Send the aforementioned 0x62D message
  6. wait 200ms
    7 change to mode 3

That should wake my vehicle up? I sometimes get random message the first time I try it, but not the same message or even the same volume as when the Onstar wakes it up, or I open a door, insert key, etc.

I’ve also tried sending the 62D with the data mentioned in this post: Here

I hooked up my M2 to my desk power supply and looked at voltage on the SWCAN pin (not attached to a bus so might be why I’m seeing this).

When the M2 first boots I get 0V on the Pin 1 of OBD
I switch to Mode 2, and still 0V
I send the 100 Wakeup, and I read 7V on Pin 1 (Verified 12V at VBat yet)
the 7V stays after the Wakeup is sent, and if I switch modes back to 3, it goes down to about 3.1V and stays there regardless of what I send.
Im using just a multimeter so I understand I might not pick up the varying voltages during a transmission, however I find it odd how it goes to 7V and stays. If I switch back and forth between modes the voltage on the bus will continue to swap between 7V and 3.1V

EDIT: I hooked up the multimeter while plugged into my silverado - and I get different behavior voltage wise, which doesn’t surprise me I guess. When bus is idle it reads 0V on SWCAN. When I wake it up by opening a door it bounces from roughly 1.5 to 2.5v which seems right (for reading from a multimeter anyway). I don’t see the 12V wake up at all which is probably happened too quick. However when I put the M2 in mode 2 with the bus asleep, and send the 0x100 wake up, I don’t get any voltage change. It stays at 0 and no frames come through. I did hook the M2 up to a Arduino Due with CAN and I can receive frames from the M2. The due is not SWCAN though so no testing the HVWU of course.

Any ideas? Seems like I’m doing the same thing as most others, but obviously got something wrong, or its hardware issue.

Sorry for the long winded first post…hopefully this make sense to someone and I can get it working!

P.S. I got my feet wet with SavvyCan as well…what a powerful tool…wish I would have found this a long time ago!