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

[M1Gunner]

Have you tried putting the vehicle in neutral and starting it? A faulty neutral safety switch could cause this as well.

 

[Alberta Tahoe]

I had gone through your wiring diagrams, the one related to the starting circuit specifically, and saw a few things I have to investigate. The neutral safety switch being one of them. There is also another ground up on the passenger side frame that I should look at.
If I have to, I'll rewire everything through a bank of rocker switches like the race car. I'm hoping (and thinking) that it won't come to that.
Speaking of racing, I was talking with one of my racing buddies yesterday and asked what happens when you transplant one of these engines into a different chassis altogether? Take the engine, all of the accessories and the PCM and get them to work in a 66 Impala (as an example). There's a lot of work that would to be done in the PCM for that to happen. If I had that expertise and tooling, figuring this out would be easy.

 

[Alberta Tahoe]

By the way, that starting circuit schematic has been very helpful. Is there one that's similar that shows all of the circuits related to the ignition switch?
Despite coming back to a truck (after two weeks away) and finding all electrics dead, I can't help but think that replacing the ignition switch as I did, hasn't complicated things and created a new problem compounding the intermittent electrical short that started this whole thing in the first place.

 

[PG01]

Throwing this out there, did you check the fuse block underhood, start run relay, etc for corrosion.... do they pull apart on nbs’s? I don’t remember .... just an idea

 

[Alberta Tahoe]

Checked all of the fuses and relays. Flipped the fuse block upside down to look for possible problems there as well. From a corrosion standpoint, everything looks good. Any testing I've done done (as in jumping over the negative cable with a booster cable from the battery to the block), adding a firewall to block wire or removing , cleaning and reinstalling several grounds, have resulted in no change.
Seeing as I can "hot wire" the starter and get the engine to crank indicates to me that the power and ground circuits to that point are sound.
I still have another grounding point (that I'm aware of) that I'll check later today. Considering the original problem was intermittent in nature still leads me to think that it's a loose connection somewhere. But now with this latest no start condition, I can't even get back to that point.
Thanks for the suggestions just the same.

 

[swathdiver]

For $300 you can buy your own Tech2, an indispensable tool in working on these trucks. Within minutes it can find the sources to your problems. Multiple codes have been thrown based on the descriptions given but we need at the least a scan tool that can read the chassis and bcm in addition to the engine and drivetrain.

Where do you live? Maybe there's a member nearby who can help?

 

[Alberta Tahoe]

I've got a scan tool although it's not a Tech 2. And from what GM tells me, when I visited their service counter and spoke with a senior tech, that I've disconnected the battery along the way and also re and re'd the PCM, any codes would be lost. That's what with my scanner says too.
Interestingly, prior to all of this no start condition, my scanner would not demonstrate any trouble codes despite the check engine light being on. I do have a CAN bus compatible scanner so in that regard, I don't know what was going on.
I do agree however, that perhaps getting onto some software that can open the PCM, (whether a GM Tech 2 scanner can do that I'm told isn't likely) would be of infinite assistance.
I have the option of towing the truck to one of the local "tuner" shops that specialize in adapting the modern engine platforms into older infrastructure. Whether they can help or not, I haven't investigated. I still haven't given up on finding the cause and the remedy myself.
Thanks for replying. I'm interested in any and all responses.

 

[swathdiver]

With all that's going on I doubt that your PCM (Engine control Module) is the problem. Your BCM (Body Control Module) is where the codes we're looking for will likely reside. When they set, they do not light up the dash light. As mentioned earlier, could also be in the chassis or other modules.

Get it to someone well trained and experienced with your old truck and who has the Tech2 as well.

There's a code for everything now, when you're truck got squirrely when it went over the bump, it set an internal code, probably a ground fault code.

 

[Alberta Tahoe]

It's finding someone that's proving difficult. I am little wary of the dealership. At $180+/hr, it wouldn't take a technician long to rack up enough time for me to purchase a replacement vehicle altogether.
I'm in agreement with ground fault and BCM. Most symptoms point to that. I've only muddied the waters by replacing the ignition switch. That it was completely drained after two weeks of sitting was the real surprise as it had sat for that length of time several times before without issue.
Maybe it was struck by lightning....

 

[swathdiver]

Well, for less than two hours labor, you can buy your own Tech2 and save a fortune:

https://www.aliexpress.com/item/201...lgo_pvid=44838909-5233-4d96-a5f0-32821f5d41bd