Getting Started E38?

[Fixed until broken]

I am coming from the older LS1 PCMs, and I want to get one of the newer ones up and running on my bench. Im not completely sure where to get started, so I figured I would ask the experts.

Goal: I want to learn about GMLAN and play with an instrument cluster. I have a few different GM truck clusters to play with here. I recently did a video about J1850VPW and capturing frames from the PCM. I want to do something similar with GMLAN.

Questions:
Is it like the older PCMs where I can give it power and it will come to life or is going need other modules as well?
What ECU/ECM would be best for my above goal? I assume it is something Pre2010 because of global A. I am not an expert here; I have never owned anything newer than 2003 from GM. I was thinking E38.
If this is achievable (getting the ECM running on the bench), does anyone want to sell an ECM with pigtails? IDC, if all the injector drives work, I mostly just care about sensors and getting it running.

Thank you in advance!

[ironduke]

E38 can be used on the bench all by itself.. There's pinouts on the web, I can find something if you have trouble finding anything.. All you need is the black connector.
2 CANbus lines, a ground, a battery feed and an ignition feed. fairly simply.

You will want to have the ign feed switched if you plan on screwing around with writing anything to the eeprom like changing the vin. You need to turn it off for 30 seconds or so to allow it to be written.
If you look on ebay an E38 with a connector is probably fairly cheap. With some small exceptions they are all the same, you do have to watch performing OS swaps from different year ranges though as you can soft brick them. There is a way to get them with brute force(up to 7 days) or if you want to pull the cover you can use BDM and fix them pretty quick.

Most modules on the low speed do not have an ignition feed and either need to be powered up right before you try talking to it or have a wakeup signal send over the pin 1 gmlan. I have found that a test light to b+ tapped on the low speed lan wakes up everything pretty good too. Not saying to do that but I have done it plenty of times on modules I don't care about and I am just playing with. Radio's, IPC's, RDCLR's, etc. BCM's do have an ign feed so they stay awake and if you have one in the ckt it tends to keep the other modules awake as well.

[Fixed until broken]

Perfect. I found a E38 on EBay with pigtails for $35 shipped so I grabbed it!

I noticed, playing with the cluster, that requesting the HV wake signal gets a response from the cluster.

I haven't played much with single wire can and its hard to find too much information out about it on youtube and stuff. I made a little module to that will work with an aduino to play with single wire can. Its https://github.com/garnerm91/SWCAN/ here if you care to see it. The main reason I made it myself is to have the th8056kdc on it. I have a few built up if anyone wants trade

Edit: Found this so I need more than just the ECM

SERIAL DATA GATEWAY
The BCM in this vehicle functions as a gateway or translator. The purpose of the gateway is to translate serial data messages between the
GMLAN high speed buss and the GMLAN low speed buss for communication between the various modules. The gateway will interact with
each network according to that network's transmission protocol.
One example of this necessary communication is the communication between the ECM/PCM which is high speed serial data and TDM which
is low speed serial data. If these modules can not exchange information, the vehicle will not start.
Communication between the BCM and a scan tool can be on the high speed GMLAN network or low speed GMLAN network. If one network is
lost, the BCM can still communicate with the scan tool. A lost communication Diagnostic Trouble Code (DTC) typically is set in modules other
than the module with a communication failure.