Hi Guys, I recently replaced the engine in my 2011 Sonata 2.4 se, since then it seems as though electrical issues have been non-stop, Ive replaced the battery, and about to replace the alternator. I charged the battery overnight to get it to start to get back from a trip to St. Louis over the weekend a got home (3 hour drive) without any systems failing. However soon after the radio and display went dead, power steering went out and the abs threw errors. So today when i went to put the charged battery in to take it to be tested i came across something that threw my alternator theory. the engine would not even try to turn over, and the small mileage display and error lights came on for about a second followed by the shutdown animation. without the brake pedal depressed the car wouldn't even turn on accessories like radio or headlights, but power locks, seat adjusters, and security lights still worked fine, along with the "no key detected" notification when I kept the key outside. Ive tested all fuses and tried holding down the ignition for 30 seconds. Anyone have any ideas?

 

5 or 6 years on the road ... enough time to cause corrosion on cables and terminals and grounding points.
Would suggest to clean all of those things.
Terminals on alternator, terminals on starter
Just remember to disconnect battery before doing the work

All the weird stuff is usually due to low voltage
It can cause all sort of weird things to happen
First get everything cleaned up. Even the grounding strap on the engine
But especially the grounding strap that connects from the battery to the chassis

Good luck

 

Just checked the terminals, all look tidy and shiny, grounding straps are tight and clean.

Scratch that, you are a lifesaver, insane such a small thing can fix such a massive issue

 

Thank you for the update
Really appreciated