I would guess alternator, only because the symptoms match what GM W-body cars - which were notorious for bad alternators - would do. Also, a car with a good alternator and a battery that is borderline but not shorted should be getting enough juice to its accessories. I am a bit surprised that the battery warning light didn't come on.

I hope it gets resolved soon for you. I'm actually glad you got that warning message, as that takes away the intermittent nature of the problem, hopefully making it easier for the dealership to diagnose and resolve. Best of luck - please let us know how it turns out.

 

A bad alternator would run until the battery dies.

 

So as of right now they said it was a loose battery terminal. When it disconnects slightly a voltage dip occurs. The voltage drop caused a ton of ecu faults. No check engine light but every single system in the car reported a fault to the ecu. They didn't charge me for that. But what we decided to do was to also flash the ecu with an update. I guess it changes a few things like shift points etc. They are only going to charge me the diagnostic fee. I go pick up the car on Friday. I'll report more when I get it.

 

Good stuff^^

 

I had the same problem on my recent road trip. There was the same reason - loose battery terminal. Thanks to this post, I could quickly isolate the problem, and at the same time save time and money.

 

Occam's razor: Loose battery terminal! Thanks for help!

 

I had the same problem yesterday as I was driving on the highway... Pretty scary to lose power steering. I turned out to be a loose battery cable from when I got my spark plugs changed. Thanks

 

hey man I’m having this same exact issue going on with my car now, did you ever solve this and if so how?