DVOM.........

Stick the battery....... What voltage we got ??

Keep red lead on battery post,,,,,,,, touch black lead to engine metal....... what voltage we got ??

BTW,,,, Finish EDIT your profile to reflect your 2007 Sonata 2.4L --or-- 3.3L,,,,,, along with location so we know which market you reside / operate in

 

The garage replaced the main relay, ignition switch and ignition cylinder. Still no change.

Ah, the old lets just pick some random parts and replace them method of fault diagnosis :laugh:
I hope they didn't expect you to pay them for their incompetence.

Does anyone have any idea what I can try?

You might try finding a garage with some techs that at least know the basics of how a car's electrical system works.

 

Engine immobilizer issue ???

 

Only car of that era was AZERA...

 

Do you get the immobilizer icon light lit up on the instrument panel with "key on" position? Something similar to this should be lit on your cluster before trying to crank the engine.

https://www.yourmechanic.com/article/what-do-the-immobilizer-warning-lights-mean-by-spencer-cates

Look at this video and see that he had better luck once he flipped the key around - probably the key chip was damaged somehow and orientation gave the receiver a better signal???

 

i get no lights on dash when I turn the key. Radio doesn’t come on. Doors do not lock or unlock, door chimes don’t work, mileage indicator doesn’t come on, truck button doesn’t work. The car is so dead it’s like there is no battery in the car.

The garage it’s at said the battery showed 12v when they put a gauge on it.

 

i get no lights on dash when I turn the key. Radio doesn’t come on. Doors do not lock or unlock, door chimes don’t work, mileage indicator doesn’t come on, truck button doesn’t work. The car is so dead it’s like there is no battery in the car.
That because you have no electricity... no electric,, nothing light up or function...

The garage it’s at said the battery showed 12v when they put a gauge on it.

Do you have a set of jumper cable ??

Yes,, Good...

Put a black clamp on negative battery post,,,,, take other black clamp and put on something metal on engine... V6,, one of the stud that stick up through engine mount at top (engine side) should serve purpose...

DO WE have electric now ??

 

Can you do the battery voltage and ground wire test with a voltmeter like sbr711 suggested you do? Put leads from voltmeter onto battery posts, should read about 12.6 VDC. Now leave the red (positive) lead on the battery post and move the black lead from voltmeter to a couple of engine bare metal spots. Do you still have the 12.6 VDC?

 

Bum ground circuit..

Follow cable from battery negative post over to fender...

Remove battery, and remove 2 bolt holding lug to painted panel...

Grind away paint to bare steel (paint is an insulator),, slap some grease on the bare steel (clean steel is a conductor) and assemble lug back to panel.. There another lug there adjacent to battery tray at left frame rail,, same paint remove procedure..

If you to go a step farther,, other end of frame rail strap is on top of auto trans case,, clean it of corrosion

Find cable at right side,, and clean it also (strut tower I think it is)

 

I love how this poor guy takes his car to a garage but has to turn to an internet forum for advise about how the garage should go about diagnosing his problem. Then, when "we" fix his car the garage will expect him to pay "them".


Sorry, I just hate incompetent people that masquerade as motor trade professionals.

 

Totally agree, I think the mechanic he is at is totally incompetent on electrical issues from the info provided thus far. I can understand repairs are difficult when fighting intermittent issues but this constant "no electrical power" issue should be very easy to locate. If the battery is indeed good, then it's just a matter of probing cables to see where the loss of continuity occurs.

 

Lets see a copy of the receipt from the shop to see what PN's they replaced and what they troubleshooted to determine that those components needed replacing.