This is a copy of a post that I put onto an Oz newsgroup, but maybe
other Hyundai owners can commet:

The Sonata is off the road until it can be towed to the service
dealership on Monday.

Appears to be the body computer has developed a mind of its own -
should I rename the car HAL? About 6/12 ago I got the "check engine"
warning light and I had absolutely zero acceleration. The workshop
said it was the throttle position sensor, and I assume a good shot of
CRC 2-26 was applied as it was quite OK after that. Then a week ago,
it reappeared (warning light and throttle prob) but along with the
"ESP Off" light. A few quick thumps on the accelerator cured the
response problem. After a while the ESP light went off. Just as I
arrived home the check engine light went off. Next day, I went to get
into the car and noticed the brake lights were on - car was empty and
locked. Huh? But only the two in the rear quarter panels, the mid-
mount one wasnt on at all.

OK, they went off by the time I got home. But apparently during the
night, Mr Ghost Driver sat there and applied the brakes all night.
Flat battery next morning. As it was 3 years and a bit old, to be on
the safe side, I got NRMA to deliver a new battery - I was hoping that
maybe a flattish or defective battery can cause strange symptoms as it
did in a friends Nissan, and that disconnecting the battery could
cause a system reboot and maybe fix the problem. No such luck. As soon
as the new battery was connected, the rear brake lights came on. But
not the mid-mount again. The NRMA person pressed the brake, still no
lights. Then went out ( or went on, can't remember now) when he took
his foot off.

Now as I consider it too dangerous to drive with the brake lights
giving false indications, I have ordered a tow truck to pick it up Mon
morning. Reason I post this here, is there anything I might be missing
so that I dont walk into the service area with a complete "DUH" look
on my face?

 

On Jan 2, 1:19 am, Steve Oz <stephen.ma...@gmail.com> wrote:
> This is a copy of a post that I put onto an Oz newsgroup, but maybe
> other Hyundai owners can commet:
>
> The Sonata is off the road until it can be towed to the service
> dealership on Monday.
>
> Appears to be the body computer has developed a mind of its own -
> should I rename the car HAL? About 6/12 ago I got the "check engine"
> warning light and I had absolutely zero acceleration. The workshop
> said it was the throttle position sensor, and I assume a good shot of
> CRC 2-26 was applied as it was quite OK after that. Then a week ago,
> it reappeared (warning light and throttle prob) but along with the
> "ESP Off" light. A few quick thumps on the accelerator cured the
> response problem. After a while the ESP light went off. Just as I
> arrived home the check engine light went off. Next day, I went to get
> into the car and noticed the brake lights were on - car was empty and
> locked. Huh? But only the two in the rear quarter panels, the mid-
> mount one wasnt on at all.
>
> OK, they went off by the time I got home. But apparently during the
> night, Mr Ghost Driver sat there and applied the brakes all night.
> Flat battery next morning. As it was 3 years and a bit old, to be on
> the safe side, I got NRMA to deliver a new battery - I was hoping that
> maybe a flattish or defective battery can cause strange symptoms as it
> did in a friends Nissan, and that disconnecting the battery could
> cause a system reboot and maybe fix the problem. No such luck. As soon
> as the new battery was connected, the rear brake lights came on. But
> not the mid-mount again. The NRMA person pressed the brake, still no
> lights. Then went out ( or went on, can't remember now) when he took
> his foot off.
>
> Now as I consider it too dangerous to drive with the brake lights
> giving false indications, I have ordered a tow truck to pick it up Mon
> morning. Reason I post this here, is there anything I might be missing
> so that I dont walk into the service area with a complete "DUH" look
> on my face?

I'm guessing the dealer replaced your brake light switch. Both the
ABS/ESP unit and the engine control module monitor the brake switch.

The switches on many '06 and newer models-- NF was introduced as an
'06 model here-- have proven to be defective despite Hyundai issuing a
TSB that most of the problems are with the switch adjustment. My
finding is that there are primarily two modes of failure: either the
plunger sticks in, or it extends but makes no contact.