Driving last night noticed that the cruise would not engage. After a few
moments noticed that the rear center brake lamp was lit. Also noted that
light didn't change intensity when I braked or when I tried to pull the pedal back with my foot.
Stopped and performed some simple checks with all power off: Engage brake and all brake lights
work fine, also noted that interior dash and lower level interior lamps illuminated and exterior side
and parking lamps came on when depressing brake.
Turning on park lamp switch illuminates all three brake lights too, again all
power off as key is out of ignition in "Off" position. I have seen some odd
light issues in the past with multi-function switches. Just curious if anyone on this forum
might have had a similar problem caused by a multi-
function switch malfunction. Cruise works fine in daytime with lights off.
Turn signals work fine day or night in normal operation and hazards work
fine in all conditions. My first thought is that the multi-function switch is where the brake,
park and interior lamp voltages would come together
and maybe a switch failure could allow the signals to short to each other.
If someone has experienced this one, please advise. Happy New Year.
Regards..

 

There's a recall on the stop lamp switch. Many Hyundais are part of the recall. I'd get it replaced by the dealer as part of the recall. That should solve your problems.

More info: https://www.hyundaiforum.com/forum/g...e-lights-6251/

 

Thank you, I will follow up tomorrow w/dealer and advise
of final outcome.

 

Called the Hyundai customer service folks and they indicated that my auto wasn't on the recall list. Big surprise there. Studied the factory schematics for several hours to begin a troubleshooting plan. Went to the engine side and jiggled relays, diodes and fuses, no change in symptoms. Did same to fuse panel in car, removed F14, the
10 amp fuse for brake switch, the problem was still there when I turned the park light
switch on so I put the fuse in and went to the parts store and used the OBD-II tool
to find there were no errors to help me. Drove a mile to parents' home and noted that the radio panel intensity did not dim when I applied the brakes, got out and had
dad view the back and noted the problems are all gone. Conclusion: The activity of
plugging in and out the OBD-II tool flexed the shorted wires so that all is normal for now. These types of gremlins tend to crop up when you least expect them, but for
now, I will focus on the primary fuse panel inside the car if it happens again. Dumb
luck I guess.

 

Don't waste your time. Just because Hyundai doesn't claim it's on the recall, I'm almost positive the problem is still the switch. Replace it and see.

 

OK, thank you for the information and support. Much appreciated.

 

The rest of the story: Prior to tearing into the brake light switch I contacted SBR711
for a second opinion. He advised that I check the indexing of the lamps to make sure
the dual elements were not shorting due to a misfit of the bulb base in the socket. I
went to the left rear bulb to start my testing. With the lamp assembly hanging from
the rear of the car I tested the brake and light actions that had shown me the initial
problem. Sure enough, the parking lamps and dash lights came on when I depressed
the brake pedal. The brake lights came on when I turned on the park lights. I took
the bulb out of the socket and the problems went away. I was sure that the socket
was at fault so I pulled out the ohm meter and noticed there was no short in the
socket wiring. Then I put the bulb back in and tested the systems again, the problem came back. Again, note the lamps all worked but the problem left when the
bulb was removed. Then it hit me, look at the bulb! Sure enough, the inner two
elements of the 1157 bulb were touching (they were shorted) and they were letting
voltage enter into each other's circuits. After a trip to fetch a pair of new bulbs and
installing them, the problem is a thing of the past. Moral: Do not assume that a
working bulb is a good bulb, I had never had this type of problem in the past and
only had situations where bulbs went bad when they burned out..... Anyone with a
cruise or lamp illumination issue should carefully consider this simple failure as a
potential cause of their problems.

 

I thought it prudent to place this in the forum for anyone who thinks
that a bulb that lights is a good bulb. Attached to this thread is a photo
of a dual element bulb where the two internal elements are touching.
This bulb created a lot of symptoms that would lead one to think he has
a defective Hyundai failure like a brake light switch, cruise control or
even a multifunction switch in the steering column.
The bulb lit up when it was supposed to, so how could it be the culprit to
many different problems? The dual internal elements were touching and
thus placing voltages into circuits where it doesn't belong. All of my
prior problems with bulbs has been when they stop working, or burn out.
Here is one that defies logic, only located by visual inspection after
using test equipment that verified the socket was fine without the bulb.
You might consider this issue the next time your brake lights come on
when you turn on the parking lights or your parking lights come on when
you apply the brakes or the dash lights might come on when you apply
the brakes. Things really went squirrelly with this little 1157 dual element
bulb. Never overlook the obvious when you chase a wiring problem.. FYI
I apologize in advance for the resolution, it is due to the size of the file
that is allowed here. If you would like a higher resolution photo, just send
me an email request and I will reply with a better pic:
millweigh@yahoo.com