When the ignition is turned to the on position and the dash lights come on temporarily the check engine light does not come on?

I also have the back probing pins now so I can check the connectors. I thought the low voltage dtc's were a sign that the battery was no good so I had a new battery put on today, but still got the same code so obviously something else is up.

When did all those codes show up? No wonder the MIL is not coming on, there's all kinds of modules offline, due to low voltage. Have you checked the charging system? You might have a main bus fuse that has burned out, check the main fuses at the battery as well as all of the ones in the rest of the vehicle.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

We took it and got tires, TPMS sensors and an alignment done earlier in the week. The tech said it died on him and it said to service the charging system that day, which is when the other codes turned up. We drove it home and when we got home, we turned it off and cranked it back up and the message to service the charging system when away. We took it to get another battery yesterday.

Went through the fuse block with a test light. There were a few that didn't turn the test light on, I wasn't able to tell which some applied to in order to turn on that item to see if the fuse was working properly, the ones I did know I turned on to ensure it was working properly. Could have a majority of those codes been thrown when the system cut off on the tech? Or even when I caused the system to die when I unplugged that Coil pack?

Well, there's a lot of codes there, I do see some lost communication codes. What codes come back after the battery was replaced? Because there are some random serial data codes such as the "Passenger Presence Module" - erratic and invalid serial data received, Battery Voltage below Threshold, Lost comms with Cluster, ECM problem exists, just a ton of codes that could be caused by low voltage,
Any computer is going to malfunction when its supply voltage is too low. So, the first thing to check is put a multimeter on the battery at idle and see what the charging system voltage is. You have a new battery now, so clear the codes, start it up, check the charging voltage and see what codes come back first. Turn some electrical loads on as well, headlights, rear defrost, AC, etc., those components will load the Alternator. If the Alternator is failing the voltage will drop with those loads on it. With a new battery right after start up you should see 13.6 to 14.2-volts roughly. If it starts to drop into the 12-volt range then the Alternator is not keeping up, or there is a wiring issue in between the battery and Alternator or the Alternator and the PCM which controls it.
If all looks ok with the charging system and codes come back, we'll have to check each one.
Unplugging the coil wouldn't set any codes except for that coils circuit, all these other codes could be low voltage, or a bulk connector might be corroded. I'll save the codes in your folder, so just clear them and see what happens with the new battery. There's no way to tell why it cut off on the tech, there's so many codes here.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

I'm a bit confused here, you said you had tires and an alignment done, but there are all kinds of codes here for all 4 of the TPMS sensors. Also, are your seat heaters working at all? or any issues with the power steering? Just going through this list of codes.

That is why I was wondering if these codes may have been set when I pulled the Coil pack plug, I understand just the pulling of the plug didn't cause the codes to set but when I did that, we figured I jostled something because I couldn't get the car to crank. It was as if the battery was completely dead.

We had new sensors put on when we got the tires and alignment, and they are working fine and reporting the psi that matches what I check with a gauge. Checking with a multimeter before cranking the battery was showing 12.6 Volts. After cranking and letting idle it was showing 13.86, turning the a/c blower full blast, the rear a/c blower full blast, bright lights on and rear defrost it shows 13.47 volts.

I don't think it has seat heaters or at least I don't see buttons to turn them on. Power steering felt fine when I drove it earlier to get gas.

What I have noticed with every module setting codes is the U0155 code, I didn't get through all the codes yet, I left the tire pressure ones out, if they're working okay, we won't worry about that for now. The charging system isn't as high as I would like to see it, but it's also a new battery. So, let's see what codes are set in the next few days or so. Below are the modules setting each code and you can see that most modules setting codes are setting that U0155-lost comms with the Instrument Cluster. If you have cleared all the codes already is the Check engine light coming on now? Almost all these codes are voltage related, one of them which was very concerning was the C0900 which is the ABS module voltage above 16volts. But this can be a module malfunctioning due to low voltage, especially since the ABS module has solenoids that can turn off and on very quickly, that can induce a high voltage spike like that. As for the seat heaters, if you don't have them, then the scan tool was either reading and misinterpreting codes or setting them as some default. There might have been low voltage at the Data link connector at some point as well. Just let me know what happens with the new battery. I'm wondering if the Cluster might be failing and pulling the GMLAN data network down, that's a possibility as well. Just check for codes, even if the MIL is not on.

No, the MIL is still not coming on. I will monitor it over the next few days to see if any codes set again.

Can you access the Instrument Cluster through that scan tool? If it's able to read codes from it you should be able to get into those modules to see live data and possibly special functions.

Yes, it can go into the different modules, and it gives me a list of options to go into from there. I don't quite understand everything but I will post a picture of the options when I get a chance.

There should be a function to turn on the MIL either in the Cluster module or PCM. Since the control wire is in the PCM, the function will most likely be under the PCM special functions.

I am not seeing a PCM module. I took pictures of the IPC module. Is it possible that it is called something other than PCM?

Here are pictures of all the modules listed when it does a full scan.

Yes, it's listed under ECM, (engine control module), it looks like the modules are communicating. What scan tool are you using? Is that a Topdon? A PCM listing is Powertrain Control module and usually is an Engine control module and Transmission module in one unit.

Mucar V06 is the scan tool I have.

Okay, with the back probing pins 5 and 18 at the ipc cluster plug, when I turn the ignition to the on position the test light comes on. It stayed on the whole time I had the ignition on, would it not turn off after a bit similar to how the light would act on the ipc?

I thought the check engine light was not coming on? Thats your original post. Does the light stay on after you start it?
With the Key Off, use a multimeter to see if pin 18 is shorted to ground. Just put one meter lead on pin 18 and the other on any ground. It shouldn't have a path to ground with the key off. If it does, the wire that runs from the Cluster to the PCM on pin 18 is shorted to ground somewhere.
The PCM had a MIL fault code stored, P0650 so the PCM was seeing that fault.

My test light came on when I probed the cluster, but the mil light did not and has not ever lit up since we got the vehicle. I didn't start the vehicle with the test light still hooked up so I don't know if it would have gone out. When I asked that last question about the test light staying on, I was thinking that it would go out after a bit just with the ignition turned to the on position, so I didn't think to crank the car with it probed.

It should go out after about 30 seconds on most vehicles, have any of those codes come back? There was a lot of lost communication codes listed from different modules, including the cluster, but since the MIL looks to be a LED in that Cluster, it may have burned out if there is a short to ground on the pin 18 control wire going to the PCM, the PCM gives a ground to the MIL, but it might have a resistor internal to the PCM on that ground control wire. I have never taken one of those PCMs apart. but most circuits that control components inside the PCM will have a resistor to protect the driver for that circuit.
This p0650 code setting criteria states- The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match for more than 5 seconds." So, whether the PCM monitors current flow or voltage to determine the MIL state on that control circuit, if that code is still setting the PCM is seeing something it doesn't like, that would explain why your test light didn't go out. LEDs burn out much easier than incandescent light bulbs. It only takes a fraction of a second for LEDs to burn.
There is a TSB on certain lamps not coming on, but it has to do with the fuse that feeds pin 5 which you already tested,
So, focus on the pin 18 wire for a short to ground. Just check it really quick with a meter with the key Off. See if there's continuity to ground.
If there are still all those codes coming back, there is probably a corroded connector somewhere because you haven't lost the Cluster comms completely, it might be an intermittent issue.

So, I did a scan last weekend and did one 5 minutes ago. Here are the results from last week.

And here is the scan from 5 minutes ago.

This is still a lot of codes, are you having any issues with any of these components? And just so you know, the module listed in black above is the module reporting the issues with the circuits or communications to other modules in red. So, I see some Radio codes, HVAC, ABS, SRS, are you having any issues with these systems or lights on for them?
I see a lot of Lost comms with Cluster, I think that is the Cluster having the issue and not these modules, they are just reporting that they're not getting a response when pinging the Cluster.
Does your other scan tool report like this?

I was thinking the lost comms with the cluster was due to me unplugging it before back probing it, which is why I also included the code report from the week before. There are some codes that make sense like the ones for the side view mirrors, we can't adjust either side using the controls on the door. I figured the HVAC error could be the reason why we get cold air regardless of what temperature we set the system to. My other scan tool is a lot simpler and does not report all the codes since it appears to only interact with the engine or transmission. I don't think the vehicle has heated seats; I think some components were changed out to fix things but maybe they come from vehicles that had options this one does not. Like the rear entertainment system controls have heated seat symbols and looking at the live data pushing and holding them buttons show them as active, but I don't believe the seats ever got warm.

Well, the lost comms is only with those specific modules that are setting a code for it. If the Cluster was completely offline the PCM and other modules would be setting the same code. The GMLAN low speed network is divided up into sections, so there could be a network splice that has some corrosion or resistance in the circuit causes those networks to set the codes. The 1st diagram below shows all the low speed 1 wire network which has all the lower priority modules on the Green wiring. The 2nd diagram is the GMLAN high speed 2 wire canbus type network for the high priority modules, PCM, TCM, ABS, etc., due to safety.
The HVAC has quite a few temperature sensors that feedback to the HVAC module, we can try to track down the circuit issue if you want to get some heat going in the vehicle. You could go into that module and check the live data for the temperature sensors, one of them will be reading far out of range compared to the others, the module probably defaults or shuts down when codes like that set. With the Auto A/C system, I'm seeing about 9 temperature sensors, some are for the rear HVAC system. If you can find a sensor that is out of range, that's the one we could try to find and get some heat going. Or wait until fall if you want. I'll check that code out though. As for the MIL, I know that LEDs have to have a current limiting resistor in series with them or they will burn out. So, if that PCM control circuit shorted to ground and the protection resistor is in the PCM on that control ground circuit, I can see the test light staying on more than the 30 seconds and it burning out the LED. I have burned my share of LEDs building circuits,

There was actually 3 TSBs on that code, it calls for a reprogram the HVAC module not replace it, so that would be good if its just a software glitch.
It actually looks like this B0433 is for the rear Aux air temperature actuator. Not sure why its effecting the front hvac, technically it should only disable the rear aux actuator, so it might just be a reprogramming issue.