No crank/start/anything condition with radio also in locked mode.

[Alberta Tahoe]

I've not managed to find the problem. Now that said, I've spent very little time working on the vehicle. I've replaced it with an 03 Tahoe, which not surprisingly has developed a few electrical gremlins of it's own.
As for the original problem (on the 06 Tahoe) I purchased a Tech 2 scanner from overseas but have to crack the box open. This will be a project I'll tackle later in the fall. Hopefully, my to do list will have diminished by then. New house (old house actually). Hobby hot rod. Current daily driver, etc...
Thanks for the inquiry though. I always like to finish up a thread with some kind of conclusion. I'll be sure to post up if or when I get it running. I have a mechanic acquaintance who was a GM line technician for several years. He says he can get it going but I've yet to pull the trigger on that. There are so many things to investigate, and re-investigate for that matter, that I'd like to revisit the pile of parts and eliminate what the problem isn't.
Time will tell.

 

[swathdiver]

Get familiar with the Tech2, hook it up and check it out while driving, combine the Tech2 with the shop manual and you'll begin solving problems quickly without being wasteful with money.

 

[Alberta Tahoe]

My hope is that the Tech 2 will help pinpoint the cause of the no start /no crank condition. At this point (and I've since abandoned the project for the time being) not getting the vehicle started is the frustrating part. Once its up and running again I sure that other troubleshooting will be straightforward.

 

[swathdiver]

My hope is that the Tech 2 will help pinpoint the cause of the no start /no crank condition. At this point (and I've since abandoned the project for the time being) not getting the vehicle started is the frustrating part. Once its up and running again I sure that other troubleshooting will be straightforward.

The Tech2 should uncover the problem rather quickly.

 

[Alberta Tahoe]

#4, unplug cluster, wait 10mins, and plug back in.

Why did you unplug the cluster? What it because of the new BCM? I don't see it as part of the Passlock re-learn procedure.

...Although our keys look like Passkey3 we have a Passlock2.

Certainly doesn't look like it.

Now that said, trying the relearn procedure for Passlock III didn't get me anywhere. The security didn't stay on as suggested in the instructions. So there was no waiting the 10 minutes until it went out as it came on and went off within seconds of being in the start position.

 

[Alberta Tahoe]

The Tech2 should uncover the problem rather quickly.

Unfortunately, no.
The Tech 2 shows that no DTCs are present.
It does show issues with DTCs having been thrown however the specific numbers are not present.
With the battery having been removed and replaced (numerous times) since the vehicle last ran, which was more than a year ago, as well as the PCM being removed once for an inspection, I didn't expect the codes to be there anyway. Tech 2 or otherwise.

 

[swathdiver]

Unfortunately, no.
The Tech 2 shows that no DTCs are present.
It does show issues with DTCs having been thrown however the specific numbers are not present.
With the battery having been removed and replaced (numerous times) since the vehicle last ran, which was more than a year ago, as well as the PCM being removed once for an inspection, I didn't expect the codes to be there anyway. Tech 2 or otherwise.

Weird. I was poking around mine the other day and found a whole bunch more features that I did not know were there. Have you been in the security area under all of the menus?

 

[Alberta Tahoe]

I've been through a maze of menus. Undoubtedly there are more still.
In the middle of it all, the Tech 2 started to malfunction. I suspect perhaps low battery as it was plugged into the 12v outlet. Interestingly, power is not available through the ALDL.

 

[Alberta Tahoe]

Interestingly, power is not available through the ALDL.

I've solved that problem with a new cigarette lighter fuse. There is however no communication with the PCM or any other devices.
My thinking is that the vehicle has sat for so long, outdoors in all manner of weather, that electrically, it's probably very corroded. Trouble shooting the no comms involves testing connectivity on several modules so undoubtedly the connections need attention. On top of that , this whole situation started with an intermittent electrical issue that was never diagnosed. Add to that that I've replaced the electrical portion of the ignition switch and am not able to do a relearn due to some other problem. The indication there is that the security light does not stay on with the key on so I can't get past step one in the relearn procedure.
So where I am at is having to go at all the devices in the string until communication is established, then start to dig into where the no start issue comes from.
Or put faith in the former GM line technician that I've dealt with in the hopes that he's had an "aha" moment in a similar situation. I'll invest a few bucks to give that I go should I not be able to resolve it myself (the interest in which is dwindling daily).

 

[Alberta Tahoe]

Well, it's been a long time since that post. I'd also started another thread in the same vein and I'll address that one as well.
In the interim the 06 was parked (the one with all of the issues) and I resurrected the 03 as a daily driver. Then the 03 was stolen (in May of 2020) so I had to revisit the 06 again.
Short story: Issue one was the intermittent electrical drop out going over bumps.
Issue two was the odd behavior of the instrument panel and a no start condition.
Issue three was not being be able to communicate with a Tech2 scanner.
Summary: Issue one traced to the ground wire in the throttle body (plus whatever else) which landed on the rear of the cylinder head. One this was resolved issue two was identified as an internal fault in the battery. This despite the battery indicating a full charge of 13.8 volts as well as passing a load test. Once the battery was replaced, all instrumentation etc. returned to normal. Issue three was never resolved as the Tech2 was also stolen when the 03 got jacked. FTR, the 03 was found less than 24 hours later however, the tools and contents were not. I think it's a reasonable assumption that the scanner communication would have been normal had the battery not being off in some way.

The 06 has been returned as my daily for the last couple of years and despite having 450,000 kms/275,000 miles is still chugging along (touch wood!).

Anyway, maybe this will help someone searching for a solution to similar problem.