Brake lights quit working. All fuses and bulbs are good. There is a blue wire labeled "electric brake" hanging by the pedal switch. where is this supposed to go?

No relay's , wiring problems maybe . Viewing wiring diagrams an using a DVOM - digital volt ohm meter to test the electrical circuits is the way to find the problem . Blinkes flashing fast would indicate a bulb out or wiring problem or the switch .
Basic Electricity for Service Techs Ohm law Current Flow Opens Shorts
Electric Testing Techniques You Need to Know

Free wiring diagrams here http://www.bbbind.com/free-tsb Enter vehicle info. year , make , model an engine size. Under system click on lighting , then under subsystem click on turn signals . Click the search button ,then the blue link .
The brake light's not working could be the brake light switch ,located on top of the brake pedal arm (linkage) . Test for B+ voltage into the switch an out when pushing the brake pedal .

You either have a bad brake light switch or a bad fuse that powers your brake lights. Go to your fuse panel and check the fuse first. If it checks good then check the brake light switch. The switch will be located on the brake pedal at the top. There should be two wires into the switch. One will have power at all times. as you depress the brake pedal it makes the connection in the switch to the other wire which then sends power to the brake lights and illuminates the bulbs. Use an electrical tester to make sure you have power in and power out when the brake pedal is depressed.

Check System Fuse - A fuse is used to protect the brake light circuit from amperage overload. If the fuse has failed it will not allow the electrical current to continue to the brake lights. To check the fuse, first locate the brake light system fuse in the fuse panel which is either under the dash or under the hood in the power distribution center. Connect the test light to a ground like an engine or dash bracket and turn the ignition key to the "on" position. Using the test light probe both sides of the fuse. If the test light illuminates on both sides the fuse is okay continue onto the next step. If one side of the fuse illuminates the fuse has failed and needs to be replaced. If the fuse fails as soon as it is replaced or when you apply the brake pedal the brake light electrical circuit is shorted to ground. Rarely a system short can occur, a car repair manual is needed to find the wiring schematic for the brake light circuit. Once the brake light wiring has been located inspect and repair as needed.

Check Brake Light Bulbs - All cars have three brake light bulbs that create the brake light illumination affect. If all of these brake light bulbs fail no brake light operation will occur. I know what you're thinking, you might say all three brake lights at once? But in reality one brake light went out at a time and you did not notice. People only tend to notice something when they almost run into the back of your car to help persuade them to inform you the brake lights aren't working. Remove any of the brake light bulbs to confirm the bulb is okay or burned. After the bulb has been removed inspect the filament and replace if failed. If the brake light bulbs are okay continue to the next step.

Checking the Brake Light Switch - A control switch is used to connect the brake light electrical circuit. This switch is located near the brake pedal lever. Basic switches have just two wires, power in and power out to the turn signal switch. Use a test light that is grounded and with the key in the "on" position test for power at one side (wire) of the switch, then press the brake pedal while testing the opposite side (wire). It should illuminate the test light, if electrical power is connected through the switch go to the next step. If no power is detected through the switch the brake light switch has failed and replacement is required. If your car is equipped with more than two wires integrated into the brake light switch a car repair manual is needed to locate the proper brake light circuit wiring.

Hi, your van does not use the signal filaments for the brake lights. You must have a wiring issue. Check for power at the brake light switch. If you have power there, the wire is broke from the switch to the S304 junction. If there is no power to the switch, the wire is broken between the fuse box and the switch. Please let me know if you have more questions, and thanks for using FixYa.

check fuse box first then bulbs or the switch under the dash that engages when you apply the brake pedal

WITH A GOOD FUSE TESTER, TEST ALL THE FUSES FUSEBOX UNDER THE HOOD & INSIDE THE VEHICLE. IF THE FUSES ARE ALL GOOD WITH THE TESTER YOU MUST HAVE A BAD BRAKE LIGHT SWITCH OR A BAD TURN SIGNAL SWITCH. THE BRAKE LIGHT CIRCUIT GOES UP THROUGH THE TURN SIGNAL SWITCH & THEN TO THE BRAKE LIGHTS. FIRST OF ALL IS THE BRAKE LIGHT SWITCH GOOD ? THE ORANGE WIRE FEEDS THE BRAKE LIGHT SWITCH, THE WHITE WIRE PUTS POWER TO THE TURN SIGNAL SWITCH, SO THE LIGHTS CAN BE USED AS TURN LIGHTS OR BRAKE LIGHTS. , PUT A TESTER IN THE WHITE WIRE & PRESS ON THE BRAKE PEDAL. IF THE TEST LIGHT LIGHTS UP, BRAKE LIGHT SWITCH IS GOOD, BY THE WAY THE BRAKE LIGHT FUSE MAY BE LABELED" STOP", THE FUSE LABELED" BRAKE" IS FOR THE ABS SYSTEM. TO CHECK THE TURN SIGNAL SWITCH FOR BRAKE LIGHTS, REMOVE THE PLASTIC COVER FROM UNDER THE STEERING WHEEL, PRESS ON THE BRAKE PEDAL, PUT THE TESTER IN THE SMALL YELLOW WIRE, THEN THE SMALL GREEN WIRE. IF THERE IS NO POWER IN EITHER WIRE, THE TURN SIGNAL SWITCH IS BAD.

find a guy with a good flashlight and have him look up under your dashboard. put your hand on the brake pedal, you will feel an arm which it is attached to, goes up behind the dash. high enough on the arm to avoid being kicked you will find a switch attached to that arm. it has a long life push button operation. most likely the plug has come off or the switch has died. this brake light switch is a very common item, fitting millions of GM products, so you should be able to get one cheaply at any parts store. now get that guy back and give him a 12 pack of beer to remove the old switch and put the new one in. it most likely has a simple snapping clamp-on plastic fastener, closely exmaining the new one should reveal the mystery of removing the old one.

Troubleshooting Procedures - Read Completely Before Beginning
(American Car) All Brake Lights Not Working

• Check System Fuse: A fuse is used to protect the brake light circuit from amperage overload. If the fuse has failed it will not allow the electrical current to continue to the brake lights. To check the fuse, first locate the brake light system fuse in the fuse panel which is either under the dash or under the hood in the power distribution center. Connect the test light to a ground like an engine or dash bracket and turn the ignition key to the "on" position. Using the test light probe both sides of the fuse. If the test light illuminates on both sides the fuse is ok continue onto the next step. If one side of the fuse illuminates the fuse has failed and needs to be replaced. If the fuse fails as soon as it is replaced or when you apply the brake pedal the brake light electrical circuit is shorted to ground. Rarely a system short can occur, a car repair manual is needed to find the wiring schematic for the brake light circuit. Once the brake light wiring has been located inspect and repair as needed.
  
• Check Brake Light Bulbs: All cars have three brake light bulbs that create the brake light illumination affect. If all of these brake light bulbs fail no brake light operation will occur. I know what you're thinking, you might say all three brake lights at once? But in reality one brake light went out at a time and you did not notice. People only tend to notice something when they almost run into the back of your car to help persuade them to inform you the brake lights aren't working. Remove any of the brake light bulbs to confirm the bulb is ok or burned. After the bulb has been removed inspect the filament and replace if failed. If the brake light bulbs are ok continue to the next step.
  
• Checking the Brake Light Switch: A control switch is used to connect the brake light electrical circuit. This switch is located near the brake pedal lever. Basic switches have just two wires, power in and power out to the turn signal switch. Use a test light that is grounded and with the key in the "on" position test for power at one side (wire) of the switch, then press the brake pedal while testing the opposite side (wire). It should illuminate the test light, if electrical power is connected through the switch go to the next step. If no power is detected through the switch the brake light switch has failed and replacement is required. If your car is equipped with more than two wires integrated into the brake light switch a car repair manual is needed to locate the proper brake light circuit wiring.

There is brake light switch located under the dash. It is inserted in a metal bracket that is a part of the brake pedal assembly. When you depress the brake pedal the pedal arm moves away from the brake switch allowing a spring loaded plunger to move out of the switch. As the plunger moves out of the switch a set of contacts close in the switch and turn the brake lights on.

You stated the 10amp under hood brake light fuse is good so check to see if you have power on the "orange" wire at the brake switch with pedal all the way up. Then press the pedal down and you should have power on the " light blue" wire going out of the switch.

We will start there, let me know what you find.
Regards,

if both fuse and bulbs are good after that there is a push switch on the brake pedal itself some times these stick and or fail to work at all and need replacing quite a simple operation take wires off replace switch and replace wires if you touch the two wires together the lights should come on do this before buying new switch