Weird full shut down- Update

[John H Daniel]

Driving slowly, everything shut off/ went dark. Not like losing gas or other engine shut down; all power off, dash dark. Panicked a little, got it neutral, then ultimately park and after a few seconds started up as normal. Drove home as normal. This is after an anomalous wouldn't start- seeming dead battery- a few weeks ago. Battery and alternator are less than 2 years old.
So weird to lose all power like that.
Cleaned all battery, main power and ground connections. Replaced the "mega fuse." Didn't really find a smoking gun (wire?)
High mileage 2011 Denali, otherwise in pretty good shape.
Is this a thing with these vehicles? Any known or typical issues?
Thanks for any help or explanation.

 

[Hobert]

Driving slowly, everything shut off/ went dark. Not like losing gas or other engine shut down; all power off, dash dark. Panicked a little, got it neutral, then ultimately park and after a few seconds started up as normal. Drove home as normal. This is after an anomalous wouldn't start- seeming dead battery- a few weeks ago. Battery and alternator are less than 2 years old.
So weird to lose all power like that.
Cleaned all battery, main power and ground connections. Replaced the "mega fuse." Didn't really find a smoking gun (wire?)
High mileage 2011 Denali, otherwise in pretty good shape.
Is this a thing with these vehicles? Any known or typical issues?
Thanks for any help or explanation.

This happened to me on the highway going 70 mph. Fuel pump crapped out. I used to be famous for running the tank low and seeing how many miles I could get out of a tank. No more lesson learned. 2001 YukonXL.

 

[Doubeleive]

Driving slowly, everything shut off/ went dark. Not like losing gas or other engine shut down; all power off, dash dark. Panicked a little, got it neutral, then ultimately park and after a few seconds started up as normal. Drove home as normal. This is after an anomalous wouldn't start- seeming dead battery- a few weeks ago. Battery and alternator are less than 2 years old.
So weird to lose all power like that.
Cleaned all battery, main power and ground connections. Replaced the "mega fuse." Didn't really find a smoking gun (wire?)
High mileage 2011 Denali, otherwise in pretty good shape.
Is this a thing with these vehicles? Any known or typical issues?
Thanks for any help or explanation.

the battery cables can corrode on the inside and look fine on the outside, but otherwise there is no other logical reason for these to loose all power period unless it is a severe power/ground problem.
It's possible it could extend to the ignition as that is really what says hey I am on, or not.
If it continues to happen, grab a multi-meter and start poking around starting at the power source which is the battery.
It is a process of elimination. ultimately it "could" be anything, bad module, frayed wire, etc

 

[Doubeleive]

This happened to me on the highway going 70 mph. Fuel pump crapped out. I used to be famous for running the tank low and seeing how many miles I could get out of a tank. No more lesson learned. 2001 YukonXL.

running out of gas would not cause a complete shut down, you would still have power and it would crank and attempt to start and the cluster would light up, radio would work, wipers, lights, yada yada. he is experiencing a total black out, like someone came and turned your electricity off.

 

[Hobert]

True that. I should slow down and read!

 

[rdezs]

.... I'm thinking worn out ignition switch..... High mileage, wouldn't hurt to replace it anyway. And they're not even expensive.

 

[John H Daniel]

It feels like the switch, the way it instantly goes full off and then on. Thanks for that
I didn't realize it is separate from the key assembly. Ordered one; looks super easy to replace.

 

[rdezs]

Before you remove the old switch, look up the instructions online and make sure you understand. There is a little plastic gear on the switch that has to be in the exact same position as the one you're removing. Other than that it's pretty straightforward.

 

[j91z28d1]

just do both battery cables new. around these boards that fixed about 90% of all electrical issues. with about 5% more just being loose terminals.

 

[John H Daniel]

I've seen that about the cables, and it's easy enough to do so why not. But I gotta say I feel the low vibration of incredulity. How does a whole cable go bad? The strands all part? The swaged ends come loose? Is it likely that replacing them just freshens up the contacts?
But, gotta trust the results, so I'm in.

 

[Fless]

You might try a voltage drop test to see if both + and - circuits can handle the load of a crank and what the drop is, which is likely the highest load the system will ever see (barring any aftermarket audio amp draw).

 

[Doubeleive]

I've seen that about the cables, and it's easy enough to do so why not. But I gotta say I feel the low vibration of incredulity. How does a whole cable go bad? The strands all part? The swaged ends come loose? Is it likely that replacing them just freshens up the contacts?
But, gotta trust the results, so I'm in.

corrosion eats the metal from the inside (on some), then the outside looks fine.
battery/ground cables are probably not a bad idea if they the original.
but otherwise further testing/diagnosing is preferred over throwing the parts cannon at it.
random issue's can make that very hard to do. As Fless mentioned you can look for it with ohm testing and voltage drop testing
are you in the rust belt?

 

[Scrappycrow]

If it ends up being the ignition switch and you're one of those folks who has a mass of other keys and doodads that hang off the ignition key, slim it down to the minimum normally required for operating your truck.

It's rarely as bad as the situation Ford had when folks' ignitions were catching on fire due to excessive keyring weight, but it still wears on the mechanical and electrical parts of the ignition switch.

 

[Doubeleive]

I keep mine all separate not just because of the weight on the switch but I can't stand a big clump of crap in my pocket

 

[Scrappycrow]

I keep mine all separate not just because of the weight on the switch but I can't stand a big clump of crap in my pocket

Ditto. If I didn't, there'd be five vehicles' worth (six if you count a trailer) and two houses' worth of keys in my pocket.

 

[rdezs]

In a multi-strand wire, the electricity does not go through the wire. It travels on the outside of each wire. Add in 15 or 20 years of oxidation, corrosion.... The resistance increases exponentially. Cleaning the ends of the battery cable does not take care of the oxidation and corrosion on the whole length, inside the insulation. Considered a normal wear item, just like a serpentine belt.

 

[Scrappycrow]

In a multi-strand wire, the electricity does not go through the wire. It travels on the outside of each wire.

This is true for alternating current, but not for direct current. The skin effect is basically nonexistent in the context of this thread.

 

[PPV_2018]

In a multi-strand wire, the electricity does not go through the wire. It travels on the outside of each wire. Add in 15 or 20 years of oxidation, corrosion.... The resistance increases exponentially. Cleaning the ends of the battery cable does not take care of the oxidation and corrosion on the whole length, inside the insulation. Considered a normal wear item, just like a serpentine belt.

Copper wire of any gauge should not be corroding and oxidizing to the point of failure after 15 or 20 years when not severed in a properly insulated jacket. There is a bigger problem with the design and/or quality of the oem cables GM used for this generation.

 

[PPV_2018]

I keep mine all separate not just because of the weight on the switch but I can't stand a big clump of crap in my pocket

carabiners for the win. Clip what is necessary on, clip what isn’t necessary off.. also easy to remove keys that need to be used without having to turn the truck off.

Sorry for the double post i thought it would auto-merge

 

[ETbME]

Driving slowly, everything shut off/ went dark. Not like losing gas or other engine shut down; all power off, dash dark. Panicked a little, got it neutral, then ultimately park and after a few seconds started up as normal. Drove home as normal. This is after an anomalous wouldn't start- seeming dead battery- a few weeks ago. Battery and alternator are less than 2 years old.
So weird to lose all power like that.
Cleaned all battery, main power and ground connections. Replaced the "mega fuse." Didn't really find a smoking gun (wire?)
High mileage 2011 Denali, otherwise in pretty good shape.
Is this a thing with these vehicles? Any known or typical issues?
Thanks for any help or explanation.

I have a 2012 Yukon XL that did something similar to what you describe back in 2020. Random one to two second electrical power loss that immediately cleared up. In my case it turn out to be the ECM. Bought a replacement on eBay with VIN programmed. Haven't had the problem since.