Total loss of electrical power while driving

[rmaker]

2011 Suburban LT ±157k miles.

My wife was driving to work this morning, crossed over some railroad tracks and she said that the door locks clicked, the dashboard lit up, messages appeared, and she lost all power. She says she couldn't steer and brakes were hard to press so she coasted for a minute and then all power came back on. I am unsure if the engine stopped, as I do not believe it could have shut off and then come back on, however, I also think the only reason it would be hard to steer and apply brakes is if the engine did shut off.

I have noticed at night that the headlights would dim intermittently, like a brownout, a flutter of the electrical system.

I went to swap out vehicles, loosened and retightened battery terminals, as well as braided ground cable to the firewall - none seemed loose.
Drove it straight to a mechanic for diag. but I know electrical issues can be a real PITA to diagnose and if it cannot be diagnosed with 100% certainty, I am not sure I want to keep this vehicle.

I know there are tons of "electrical gremlin" posts and bad ground posts etc..

Thoughts??

Ryan

 

[intheburbs]

Something like that major should be easily-diagnosable (is that even a word?). Something major is loose or broken.
Battery cables
Battery
Alternator
Cables leading to and from the megafuse holder
The megafuse itself - loose, damaged, etc

Or, some combination of those. A good battery will power the vehicle for a while if the alternator dies. So you might have something like a bad battery and a bad alternator or loose cable.

 

[kbuskill]

The battery cables on these trucks corrode internally and cause the exact problems you described.

Replace both cables.

 

[noodlesandsam2]

you need a bit more info than that. Reading about this - do you have an OE AC Delco Battery? I moved away from these back in 2003 with the 1500 XL - they died fast - but it seems that the acid leak that ruins the cables starts with the battery. I can believe it. I ran an Optima from late 2003 thru to April, when the 1500 went bye bye ( Frame rot was too much for me to deal with ). New to me 02 2500 has a new Interstate in it ( I don't know what was there before ), but his cables look ok.

 

[rmaker]

Update - The mechanic did a voltage drop test on the cables - all good, the alternator is good, the battery is good, he removed multiple grounds/cleaned etc., and added additional ground from the firewall to the engine block as the braided cable is reportedly very corroded. He replaced the terminal end of the negative cable, says he cut it back, and resoldered on terminals. Pulled mega fuse and cleaned, among other things. He could not recreate the total loss of power and indicated that he had not witnessed any of the "brownout" scenarios I had witnessed. I'm gonna pick it up today and hope for the best. I will drive it tonight and see if the light dimming/AC slow down occurs, if it does I'm gonna assume I still have problems. After all the time and money I have spent fixing this thing up, an electrical gremlin like this may be the determining factor on whether I keep it or not. The idea of not knowing when or if it may just lose power again is unsettling.

 

[noodlesandsam2]

Which battery do you have? If it is Delco, I would be wary. I had so much trouble years ago, and from what I read, they are not better. The 02 XL 2500 has a new Interstate, and good since I got it in April. I had 3 Optimas in 19 years ( still have the third one - in different car now ). I've had the bad ground from firewall ( body ) to block, and that made gauges act funny, but the car still ran ok.

 

[rmaker]

Which battery do you have? If it is Delco, I would be wary. I had so much trouble years ago, and from what I read, they are not better. The 02 XL 2500 has a new Interstate, and good since I got it in April. I had 3 Optimas in 19 years ( still have the third one - in different car now ). I've had the bad ground from firewall ( body ) to block, and that made gauges act funny, but the car still ran ok.

Brand new die-hard.

 

[noodlesandsam2]

How's that going? I had a Die Hard die in a BMW - 11 months - **** ( not bought by me, but based on the date codes, it was new - went Interstate AGM, and it's been good.

 

[jt8412]

2012 denali yukon xl
really hoping all of you can help us figure this out! The guys at firestone didn't believe me until I showed them the video! see the link . This car has been a mess since we bought it a year ago, needed all new evap system, new alternator... now this. Would LOVE to add 200K more miles to it and have it run smoothly for our family! But depending on what the dealership says $$$$ we might have to cut our losses and move on!

 

[Tahoe14]

@jt8412, post this in the 2012 section under “general discussion” and you should get more views to help you try to figure it out.