01 sonata 2.4. Brake lights are not working. ckd the fuse it was blown put new one in , the lights worked for a bit then stopped. ckd fuse again its good. So I figure its the stoplight switch on the pedal. put a new one on and still no brake lights. all the bulbs are good. Is there a relay somewhere? There is no cover on the fuse box to see what those relays are in the fuse panel. Can't find a diagram anywhere for the fuse panel. I looked at the tech site but could not find it.

 

Yes, I too have looked at that diagram on the Hyundai service site. I cannot figure why they would show the layout for the engine fuse box, but not include the table to decypher the fuse locations. They show nothing for the fuse box under the dash. Have you checked the owners manual? Perhaps you don't have that on hand either. You might try finding a replacement fuse box cover at a salvage yard. Some yards don't care to screw around with plastic pieces like this and will give them away if you locate it. The Hyundai service site does list four causes for brakelight problems:

Fuse 16 (10A) blown (which you've dealt with)
Stop lamp switch faulty (ditto)
Wiring or ground faulty
Stop lamp relay faulty

With a cheap multi-meter, you can diagnose a wiring or ground fault by removing the bulbs and checking for voltage between the teminals in the socket and between the positive terminal and the car body while someone presses the brake pedal. If you have no or low voltage across the terminals, but full voltage (~12 to 13+ VDC with a fully charged battery) across the positive terminal/body connection, you have a bad ground wire connection at the back of the car. If no voltage either way, I'd check for voltage at the switch. Perhaps someone else can tell you where to look for the stop lamp relay. If it's not on the fuse box under the car dash, it may be one of the relays integrated on the body control module.
[/align]

 

I found the fuse box details under the "ETM" option of the shop tab on the service site. I assume you've replaced fuse 16 under the dash, which is labeled the "stop lamp circuit". Does this car have cruise control? It looks like the brakelight circuitry feeds back through fuses 2 and 10, which also serve the cruise control system. I'm guessing the stop light relay provides the cutoff function to the cruise control when it's engaged. Also, fuse 23 in the engine compartment box is labeled cruise control and stop lamp functions. Any one of these could be your problem. I hope this info helps.