(BCM/IPC) Driver 1/ Driver 2 handshake? 03-07 GMT800

[Fixed until broken]

Does anyone know how the Driver 1 / Driver 2 handshake works with the BCM and IPC on 03-07 GMT800?
I assume the IPC requests the info from the BCM, and then the BCM sends it to the IPC, or is it just unrequested on IGN?

I have a plug-and-play box for installing the 03-07 clusters in 99-02 trucks, and I want to make the Driver 1 message display "Driver 1" instead of "Unknown Driver".

By the way, I plan to release the firmware as open source so anyone can play with the modules. I just need to finish testing this version before I release it. I would expect to see that by the end of the week.

IMG20251218194229.jpg

BTW wasn't sure where to post this but I figured I am tuning my module right?

[Gatecrasher]

This is just a half educated guess, but I would think the BCM would get the key ID from the lock cylinder and then broadcast the corresponding driver ID on the bus. I'd be surprised if there was some kind of handshake. There are some exceptions, but this stuff is usually more of a broadcast format than a request and response.

I've got some class 2 bus dumps from my 08 and 09 Hummer H3s if that'll help. I don't know if the protocol is the same as the full size trucks but maybe it's worth a shot?

[Fixed until broken]

I've got some class 2 bus dumps from my 08 and 09 Hummer H3s if that'll help. I don't know if the protocol is the same as the full size trucks but maybe it's worth a shot?

H3 is pretty much the same as Colorado, so it would share with that, but I am not sure how much of the bus is the same as a full-size bus. (H2 is the same as full size). It wouldn't hurt to look, though, so I would appreciate it.

[Gatecrasher]

I no longer have either H3, so it's been a little bit since I got these. But both files should start with key off and then go through engine start up with a few seconds of idle.

H3 had that dumb passlock sensor where the key itself didn't have any kind of identity. But maybe there's a default message that the BCM puts out that'll keep your IPC happy.

[Fixed until broken]

I no longer have either H3, so it's been a little bit since I got these. But both files should start with key off and then go through engine start up with a few seconds of idle.

I see why you no longer have that Hummer, it seems to have needed a few systems serviced lol. It was fun doing a playback of those to the cluster, but neither of them had the driver 1/driver 2 DIC message.
Playing that back to the GMT 800 cluster, I am getting a service Tire monitor and a few more messages. I did learn a couple of neat things from it, though. A8 DF 40 91 XX This will dim the displays 00-FF is the brightness for XX
I added to my list of known frames. https://github.com/garnerm91/J1850/blob ... /known.txt

Does anyone happen to have a GMT800 log that includes DIC?

[Fixed until broken]

I found it!
"88 CF 40 07 XX" with XX being 01 02 or 03. Driver 1, 2, or 3. I didn't realize it supported 3 drivers. I thought it was just driver 1/2. I found it in a random Trailblazer log I downloaded from GMTNation. I've attached the log I used. I have to trim the timestamps and CRC off my script that plays them. So it's just bare frames

[Gatecrasher]

Nice job! I'm glad you were able to learn something from my logs even if it wasn't what you were after.

For the record, I had those trucks in very good condition when I sold them.

Does anyone know if there's a standard database format for class 2 messages? Something roughly equivalent to Vector DBC.

[Fixed until broken]

For the record, I had those trucks in very good condition when I sold them.

Probably just some frames the GMT800 didn't expect or was looking for and didn't get after getting a frame from the TPS module then.

Does anyone know if there's a standard database format for class 2 messages? Something roughly equivalent to Vector DBC.

GM was not completely standardized across platforms with J1850VPW, so I don't think you will find one. SWcan was pretty standard, so you can use the GMLAN bible for that, but I have not found 1 yet for J1850VPW, and after some experiments, it seems like nothing is standard on it.