Intense Electrical Issue

[DJ BigDog]

I think @DJ BigDog was the last. Maybe he found something and can chime in?

I had been getting the P0455 evap trouble code for awhile and the tighten fuel cap message so I finally replaced the Evap Solenoid Sensor and cleared the codes and that seemed to fix my issues.

I think @DJ BigDog was the last. Maybe he found something and can chime in?

Turned out to be a bad ground cable on back side of engine to firewall. Also took out the TPS actuator solenoid. Check all grounds everywhere! And the wire harness and connector at the throttle body.

 

[Alberta Tahoe]

Thanks for that. I'll have to get into this on a whole other level as the condition has become worse.
The intermittent connection now appears to be permanent. After being away for two weeks and the truck parked, attempting to start it resulted in nothing. As if the battery was disconnected. Then the gauge function returned (with no fiddling on my part) although all indicators were at zero. Further to that, removing the key made no change whatsoever. The data centre was still active and the dash idiot lights remained on despite the key being pulled from the ignition switch.
To me , this points to the ignition switch as being the culprit but short of doing a re and re, I have no way to determine if that's the case.

 

[Alberta Tahoe]

(Copied from my other related threads)
Thinking this over and considering the real value of the vehicle to me (both in what it's worth and what it would cost to replace) I'm of the mind that buying a 2nd one that's still running may be the way to go. I've found a 2003 model and a 2001 for under $1500 either of which might be a suitable donor. At the very least I can say that they don't have the same issue mine does (in that they're driveable) and I'd have a pile of parts to swap in an attempt to isolate the problem. My thinking is that a dealer could possibly cost double that amount and still not remedy the situation.
This '06 was purchased for $5000 a little over two years ago and besides new shocks, front shock bushings and tires, it's required nothing other than oil changes and an air filter.
Still thinking...

 

[Alberta Tahoe]

(Copied from my other related threads)
http://www.tahoeyukonforum.com/threads/electrical-issue-is-expanding.93566/

http://www.tahoeyukonforum.com/threads/body-control-module.93759/

Thinking this over and considering the real value of the vehicle to me (both in what it's worth and what it would cost to replace) I'm of the mind that buying a 2nd one that's still running may be the way to go. I've found a 2003 model and a 2001 for under $1500 either of which might be a suitable donor. At the very least I can say that they don't have the same issue mine does (in that they're driveable) and I'd have a pile of parts to swap in an attempt to isolate the problem. My thinking is that a dealer could possibly cost double that amount and still not remedy the situation.
This '06 was purchased for $5000 a little over two years ago and besides new shocks, front shock bushings and tires, it's required nothing other than oil changes and an air filter.
Still thinking...

 

[afpj]

I apologize if you've done the following suggestion already, as following this is somewhat difficult spread across 3 threads.....

With battery disconnected, have you disconnected and cleaned (like with electrical contact cleaner) the bus connectors to the bcm and Pcm? Have you tried a different battery? It's almost as if you have loose plates in the battery and they short out going over bumps. Just trying to throw out 'cheap' suggestions.

 

[Alberta Tahoe]

Yes. I've spread the subject across a few threads although each one was addressing something somewhat different. I've found it to be an effective way to solicit additional responses as threads tend to go stale.
To answer your questions, (one of which you asked in another thread regarding the battery and I answered): Two batteries. Both test OK (although not loaded tested but that's not relevant here). I had thought about the battery being defective too. No difference.
You do bring up a good point regarding the connections at the PCM. It may have been mentioned before too. That is something I had on my list of "to try" but sort of had given up. I've renewed interest now that I've been away for a couple of weeks and I'll address that when I'm back under the hood. The BCM too although if you could see the dust and dirt under the hood (not to mention the moisture that must accumulate), the PCM is the more likely target.
It'll be another couple of weeks before I'm back at it.

 

[ill_noiz]

I would try installing new wire for all the electrical connections from the battery/alt. Something similar to doing the big 4 upgrade.

 

[Alberta Tahoe]

I'm not familiar with the big 4 upgrade.

 

[Alberta Tahoe]

The truck has been parked since the post above until recently. (3 years plus the one year since I started on the repair) Having my other Tahoe stolen (that's another story) forced me into fixing this one.
What happened up to this point and my attempts at repair compounded the situation and made diagnosis all but impossible with the limited experience I have on these vehicles (and I'm an old school auto technician and currently a master electrician).
So I had it towed to an independent one man shop which I became acquainted with when getting into this originally.
Ultimately the main issue was traced to the throttle body wiring harness. More specifically, to the ground wire in that harness that connected to the passenger side cylinder head.
I had complicated matters by: removing and re-installing the (same) PCM, replacing the electrical side of the ignition switch and as it turns out trying to do my troubleshooting (via a Tech 2) with a faulty (truck) battery.
Interestingly, it was this battery that led to the original no start condition that arose after having been parked for two weeks. The intermittent electrical was already an issue prior to this. The battery in question showed proper voltage. It also load tested well. It was off and on various chargers (smart and otherwise). What the battery was doing was performing as it normally would then for whatever reason, (perhaps via an internal short) would sort of half drop out. When this happened, the instrument cluster would not fully shut down, the door locks became inoperable and the ignition switch lost most of it's functionality. There were probably other issues as well but the gauges not shutting down entirely would ultimately drain the battery over a day. I never got to the point of starting from square one again as another truck purchase put this on the back burner. It was my mechanic who related this same story to me and it fit perfectly with what I had experienced in my testing. Various batteries had been in and out but as it happened, the faulty battery was in the truck when it arrived at the shop.
Anyway, to sum it up, the original intermittent electrical was traced to a poor ground and the inability to diagnose this (as the Tech 2 kept losing communication) was traced to the battery.
The truck is now back in service.