The red e-brake light is only triggered by 2 things like SoCal2V stated above. Try unplugging the fluid level sensor in the brake master cylinder as this is a quick test to see if the issue goes away. If the brake fluid in the master cylinder is dark or dirty I would highly recommend changing it out as dirty brake fluid will also cause these brake level sensors to malfunction. Of course just sucking the fluid out of the master cylinder and adding new fluid is not changing it all. When you get the old fluid out of the master cylinder and add new fluid I would then go around to each wheel and have someone help you bleed the whole brake system and get the old fluid out of the rest of the lines and hoses. During this time you can check out the condition of your brake and make sure you dont have a bad caliper or brake hose on the rear causing the tire to drag.
Hopefully this helps. I changed my fluid on my 03 GT and put new calipers, hoses, rotors and pads on the front and new rotors and pads on the rear. Changing out the brake fluid helps prolong the life of your other brake system components.