Problem with Electronics in Hyundai Elantra, Diag Cannot Find Issue

Generic Dreadhead

Hi All,

I'm hoping to turn to your superior experience here to get some advice as I'm at my wits end.
I would like to mention before hand that I have very little motoring/car knowledge beyond filling it with petrol etc.

I have a 06 Hyundai Elantra which we bought from a dealership (pretty much) new back in the day.
It was my mothers cars for years and about 2 years she gave it to me.
The car has ALWAYS been serviced in the dealership where we bought it originally.

Over the last 18 months it's been serviced 3 times. It had a Pre-Nct done (18 months ago). It had the Timing Belt changed and the motor for the windscreen wiper mechanism replaced (10 months ago) . And finally and most recently it had a new battery installed (10 weeks ago) as it had been a bit slower to start and would cut out etc more often during the likes of 3-point turns etc.

Since then it has had 3 electronic issues.

Instance 1:
Went out in the morning to go to work and tried to unlock the central locking using Electronic key. Didn't work and opened the car manually using the key. The car started ok and I was able to drive to work. 8 hours later I went to go home and it was completely dead. No dashboard lights, central unlocking not working again. I got it jumped and was able to drive home ok, no further issues for 2 weeks or so.

Instance 2
I was driving in traffic and as I was pretty much stopped (or at least absolutely crawling in 1st gear preparing to continue when lights went green) when it died. Again, no dashboard lights, power steering gone etc. My passenger jumped out and went to push it off the main road and while pushing it, the electronics started coming on and off rapidly, all the lights on the dashboard were going on and off very fast until after a few seconds the stayed on and power was restored.

After this I brought it to the Dealership where they ran a test on the new battery which showed it was at 100% charge and 100% service and they could not find any issues. They said I could leave it with them and they could check all the electronics etc but it would be a slow and labour intensive process (which would have a larger cost associated). They recommended I bring it to an Auto-Electronic Technician as they would have more comprehensive diagnostic equipment and would be cheaper.

I brought it to such a place and they could find no issue whatsoever when they hooked it up to the diagnostic equipment and they drove it quiet a lot and it didn't give any issues. They didn't charge me for this and said they secured the connections to the (I think) crank shaft or something similar.

Instance 3
Was hoping I was in the clear. No such joy. Went out last night about 3 hours after driving it home and again, central locking key didn't work, stuck the key in and no power again. In a desperate attempt I opened up the bonnet and had a nose but didn't really know what I was looking for. Closed the bonnet again and it started when I stuck in the key. I can only believe that the banging of the bonnet opening/closing somehow resolved it.

Speculation
The component the Auto Electrician re-secured (I think it was a crank something, it began with C, i'll try find this out) might need completed replacing they said, cause it could be this component (at a cost of approx €100).
There were no major cutting out issues before I got the new battery, it was a bit sluggish sure, but never really died outright.
The car cannot be left with "Lights on" etc due to the way it's designed, when you take the key out, it disengages all electronics.
The way the power has come on and off rapidly I would liken to when you have 2 ends of an electrical cable and brush them off each other.
Like when you have a plug or something halfway in and it gets a knock.
The phrase "bad earth" was thrown about by the Dealership originally.
I think that when the new battery was put in, some cable, or connector or something inside the battery is lose/crappy

Please help
I don't really know what to do.
As far as I'm concerned I've brought it to the places I needed to and as far as their concerned there's nothing wrong at all.
I appreciate that when they hook it up, whatever connection or piece that is causing issues decides it's going to be cooperative at this point so they can see no issue.
Am I right in saying that you get a 3 month warranty type thing when you bring it to a garage/dealership or is this just good will?
I feel like the Dealership were very quick to go "Oh we checked the battery, it's not the battery and we only changed the battery, so we cannot help" and as a result tried to absolve themselves of the issue.
Any advice would be GREATLY appreciated.
Sorry for the text dump, I thought I should try be as specific as possible.

Thanks,
Cormac

TL:DR: All the electronics and power steering etc are dying completely at random and without pattern and both the dealership and auto electrician can see no problems and I'm afraid to drive it anywhere cause I don't know when it will die at a destination and leave me stranded or die in traffic and leave me screwed

jimgoose

If it were me, I'd test the battery and charging system voltages.

jca

Start the engine and while its running give the cables around the battery a shake. Try and do it while its a bit dark outside and look out for any sparking, if the fault is around the battery you might manage to reproduce the fault.

DublinDilbert

Definitely sounds like a bad connection/short. I would get the schematics for the car and see which connections could cause all the problems your seeing. As your seeing problems with multiple systems there is probably a correlation.

Any forums for this model to see if others have see something similar?

Have any fuses ever blown on it?

Definitely check all ground connections and interconnections at fuse boards.

A good auto electrician should be able to figure this out, make sure to give them all of the above information in writting so they can narrow things down.

jca

Just using basic logic here which seems to evade everyone when it comes to cars. Car was running fine and then the battery started to fail which on a 9 year old car is to be expected. Battery was replaced and said car now suffers intermittent total electrical failure.... Where would be the obvious place to start checking?? Anyone?? Even the dumbest apprentice who's barely literate would be able to get a result on this problem.

Generic Dreadhead

Ok, guys, thanks for your advice.

I guess I'll just try and get the Dealership to accept responsibility for this issue as it i'm sure it's caused by the new battery

jca

Cormac... wrote: »

Ok, guys, thanks for your advice.

I guess I'll just try and get the Dealership to accept responsibility for this issue as it i'm sure it's caused by the new battery

Don't take any guff from them. Emphasise that the car was perfect until they replaced the battery.

Generic Dreadhead

Ok, what they reckon is that It's related to the Electronic key and in-car component that activiates/de-activates the central locking.

Apparently I can still use the physcical/mechanical key to open/close the car and it's central locking.

But what ever the electronic key does, it can drain the battery by getting caught in some sort of "always-active" state.

This kind of makes sense as it fits with what I experienced locking the car, coming back hours later and it being dead.

Does this sound feasible/correct/believable? Again, I'm not really a car-person