Electrical issue or computer issue on start up?

[TorontoGen]

Hi, frequent reader but first time poster.

My 2015 3.8 only has 12000km/8000 miles on it and this crazy start up problem is leaving me stranded in parking lots. Basically, I'd say 10% of the time on start up the electrical goes completely dead once I hit the start up button. Sometimes, opening and slamming the door or hood restarts the electrical and sometimes it doesn't. If it does work, my computer is reset and the clock goes back to an old time, temperature reading goes back to Fahrenheit and my climate settings are back to factory presets.

The problem seams to get worse and worse to the point where slamming the door 15+ times won't get the electrical back and I need a roadside boost. The boost somehow fixes the car for a week or so until the problems happen again. Hyundai has checked my battery and done some kind of electrical test showing things are fine. Obviously they don't get the symptoms showing when it's at the dealer. They told me I needed a new fob battery which they replaced but that didn't fix it.

I saw some other people may have this in the electrical problem thread but it's wasn't followed up on. Any ideas?

https://youtu.be/9jNYbNpmngI
https://youtu.be/-gj3Q44TU7Y

 

[balfor]

Electrical issues that are temporarily solved by movement are indicative of a loose connection somewhere. I would check the battery connections again and make absolutely sure they are secure including all power feeds off the + terminal. The dealership checking the battery probably means they looked at it but did not put a wrench to it. Also check the main + and ground connections on the underhood fuse box, from my recollection there is a single main power feed with a 12mm nut securing it, make sure it is tight.

Past that it could be a harness problem or ground fault somewhere. Since you are under warranty I would push the dealer to diagnose further.

 

[Mark_888]

I think others "may" have reported similar problems. I would search this forum thoroughly to see if you can find such complaints, and eventual fixes. I think it was something loose somewhere, but I don't remember what it was, and not something simple as the battery terminals.

 

[dougmcp]

I would video each time you start the car for the next month and then present the video and the car to the dealer. I would then refuse to accept the car back until they document repairs or take the car back under a Hyundai credit or lemon law.

 

[glennk]

Seconding Balfor's comments, I'd pull the fuses and re-insert them. Check the battery contacts in the trunk and under the hood. Maybe even the engine immobilizer? My Acura RL would get flakey when the battery wasn't working at 100%. Acura later agreed to replace the battery and the problems resolved.

 

[Mark_888]

I think others "may" have reported similar problems. I would search this forum thoroughly to see if you can find such complaints, and eventual fixes. I think it was something loose somewhere, but I don't remember what it was, and not something simple as the battery terminals.

Actually, I think I remember that it was a bad ground connection somewhere, where there was overspray on some paint that was messing up a ground wire. If you can find the thread on this, they may reveal where the grounding problem is typically located, so you can tell your dealer.

 

[Seejay]

Really sounds like a loose or bad connection somewhere...

 

[digmyGenesis]

I have the same problem. It went away after I changed the battery for 6 months. Came back again yesterday. Very annoying issue. Dealer keep asking to reproduce this. But happens intermittent.

Have you solved the problem yet. Please give me some ideas. What to look for. I checked the battery connection. It seems good. Nothing loose. But the + terminal has a red box and 3 wired going in.

 

[Suburbazine]

I have the same problem. It went away after I changed the battery for 6 months. Came back again yesterday. Very annoying issue. Dealer keep asking to reproduce this. But happens intermittent.

Have you solved the problem yet. Please give me some ideas. What to look for. I checked the battery connection. It seems good. Nothing loose. But the + terminal has a red box and 3 wired going in.

Take the negative and positive cables off and scour the inside of the rings with a wire brush. Then take the negative cable off the body at the bottom of the battery and remove the paint with a wire brush.

It doesn't hurt to remove the main positive cable from the battery block and scour those contact points too.

 

[digmyGenesis]

I think others "may" have reported similar problems. I would search this forum thoroughly to see if you can find such complaints, and eventual fixes. I think it was something loose somewhere, but I don't remember what it was, and not something simple as the battery terminals.

I couldn’t find anything. Can someone please help finding it.

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[vicarus]

I couldn’t find anything. Can someone please help finding it.

The main ECU relay is the culprit in many cases. Passenger side junction box, the black one. They run hot. Mine had an intermittent open coil circuit. The relay powers 2 electrical circuits so any 5-pin relay that fits is not the solution. Took it apart and the coil is discolored. I ordered a used junction box from eBay. You're getting extra relays and fuses to have anyway. To be sure, check all related relays.