Brake light came on then pedal got hard but would still stop. After releasing pedal it took about 45 sec. for light yo go out. When depresed again would work good until light comes on again. Have asked parts person about problem sujected master cylinder did not help. Could it be the vacuum pump or brake booster?

Your better off going by the feel of the pedal rather than measurements. Try this. With the engine off and the brake system cold remove the key from the ignition and pump the brake pedal. it should get progressively harder and your foot travels a shorter and shorter distance until its too hard to press.
Press and hold the brake pedal hard down then start the engine. You should feel the pedal soften, that's the vacuum inside the brake booster kicking in.
Release the pedal and again press it hard down, holding it there. The pedal should feel firm and not change. Release and repeat to make sure.
If the pedal has no resistance check your work as there is no pressure in the system. If the pedal is soft or spongey re-bleed the system starting with the calliper furthest away from the reservoir.

Sounds like your ABS unit on its way out.
with the engine off, pump the pedal till its hard. keep your foot on the pedal pushed down and start the engine. your pedal should become light and continue down to the "floor".

Break swich (over break pedal) malfunction/defect/loosed plugs wire.

nothing, It doesn't work like that, when your brake switch is mounted , correctly , your pedal has a bracket on it that pushes the switch plunger in so brake lights are off. when you push brake pedal in, to stop vehicle, the switch plunger (spring loaded) comes out to turn brake lights ON ! get it ? when you release pedal it pushes plunger in, to turn lights OFF !

The most widespread Hyundai recall, affecting up to 531,894 2005-2008 Accent, Azera, Elantra, Entourage, Santa Fe, Sonata, Tucson, and Veracruz models, is NHTSA Campaign 09V122000. It is focused on a malfunctioning stop lamp switch that may prevent brake lights from illuminating when the pedal is depressed (the same switch may also cause them to stay lit after the brakes are released).
Owners of affected vehicles may contact Hyundai Customer Service at 1-800-633-5151, call the NHTSA Hotline at 1-888-327-4236, or visit SAFERCAR.GOV

1. Check the fluid level in the reservoir after bleeding each wheel. Add DOT3 fluid, if necessary.
2. If the master cylinder was disassembled or if the reservoir becomes empty, bleed the air from the master cylinder as follows:
   1. Disconnect the brake lines from the master cylinder.
   2. Slowly depress the brake pedal and hold it.
   3. Block off the outlet plug with your finger, and release the brake pedal.
   4. Repeat 3 or 4 times.
   
   
3. Bleed the brake starting with the one furthest from the reservoir and then the next furthest, etc.
   
4. Depress the brake pedal several times, then loosen the bleeder plug with the pedal held down.
5. At the point when fluid stops coming out, tighten the bleeder plug to 11 Nm (8 ft. lbs.), then release the brake pedal.
6. Repeat until all the air in the fluid has been bled out.
7. Repeat the procedure to bleed the air out of brake line for each wheel.
8. Check the fluid level and add DOT3 fluid if necessary.

there are several causes, check bulbs first. A crossed filament in a bulb can cause similar problems. The brake & turn use the same filament so if the brake lights are on, due to a bad switch underdash, the turn signals won't work.

Did you adjust the brake light switch correctly? To adjust the brake light switch, first press the brake pedal down a few inches, then pull the switch plunger rod out of the switch toward the brake pedal arm, as far as you can without using excessive force. Next, return the brake pedal to the pedal stop position against the pedal stop and pull the brake pedal toward the rear to push the brake light switch actuating plunger rod into the switch housing limited by the travel of the brake pedal arm rear travel stop position. This procedure automatically adjusts the brake light switch correctly.
If the brake lights still don't turn off with the brake pedal released, check the brake pedal arm for sticking or binding that is preventing the brake pedal arm from returning fully to the pedal stop when the brake is released.

check for fuses,stop ligth switch in brake pedal and multifuncion switch wich is the one in the steering colum,depresing pedal power go up to multifuntion switch before go rear lights.GL

in stop pedal youll see the stop light switch,remove the botton cover and you will find it,check it whith a test light,it should be normaly open,so one side power and the other ground,depresed power in both side ok,GL