That the oldest one in the NF Sonata handbook... replace the positive battery cable assembly...

91850-3K111 $139.44 + applicable local sales tax... (this is the new number on the cable assembly), take you maybe an hr to replace it, all done from top..

Thanks I appreciate the fast response. Evidently the Hyundai dealership I do business with has never heard of this issue, or how to resolve it. I bought a battery from them yesterday. They said the CCA should be 770, but was only pulling 154 and that was the problem.
So now I guess I'll take care of this myself.
Thanks again.

Forgot to mention, while the battery is out, look at the frame rail right there by the battery tray..... see that cable/plate bolted to frame and heads off to the transmission... unbolt the cable, and scuff the paint to bare metal for the plate to bolt back to frame rail.. Just smear some anti-seize to cover the bare metal and prohibit rust.

Look at where the short negative battery cable bolts to fender, scuff paint to bare metal so that plate sits on bare metal, smear with antiseize prior to re-assemble cable to fender.

My Sonata had this exact issue a few months ago.

Turns out, one of my taillights had burned out and caused a short. As soon as i replaced the tail light, situation fixed.

So check to see if any of your taillights are out (or any lights at all). If one is, you probably found your problem.

Old GM cars used to have the same issues.

my 2007 sonata is having the same issue... my head lights get dim and its hard to see, i am almost scared to drive at night but i have to with my job,

Same problem
 

My wife's 2006 Sonata just started displaying similar symptoms. Sad thing is that my 2009 displayed similar stuff last winter.

Well...knock-on-wood i have had none of those issues with my 06 3.3.

Electrical System Issues
 

I have a 2006 model and 2 years ago, I had this electrical issue come up.. The dealer ship said it needed a whole new wire harness but wouldn't cover it under warranty due to the fact that a Car Starter was installed (& not installed by there preferred provider).. The speedometer was out, The company that installed the Car Starter was nice enough to spend the day figuring it out and fixing the issue. But recently the electrical is all screwy. Radio going off, blower stops, all the lights flash on/off like the Car has been turned off.? While I'm going 45/50Mph.. Gotta be a short somewhere, but can't seem to have Hyundai touch it without paying $1200+ for a harness? :mad: Any one got advice on What's the best route to take? Can't drive the car in the dark, cause the headlights cut off..

Replace the positive battery cable assembly as called out earlier in the thread... oldest one on the '06-07 book..

Radio - audi stops, but station stays set, HVAC fan up/down speed, lights dim when stopping,,,,, right ??

2006 Sonata Intermittent Electrical Problems
 

I have just test driven my son's 2006 sonata - 76k miles, and it does exactly the same (blower cuts out, radio, esc light on, lights flicker--all intermittently). we also had it into the dealership this week because the air bag light wouldn't shut off. the dealer told us it had a low voltage code and reset it.

anyway, is the positive battery cable assembly a reasonable "fix"? don't want son in harm's way! other than this, the car runs and rides great.:confused: