Weird full shut down

[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.