I'm gonna take a stab in the dark on the most common e-brake malfunction.
What happens alot, due to long periods of not using the e-brake, the levers inside the rear drums freeze. Sometimes you get lucky and they freeze open...but other times they will freeze with the brakes engaged, which is bad news.
If you go to your toyota dealership and tell them what the problem is, they will likely know exactly what you're talking about and what parts are necessary to fix the problem.
Basically you have to pull apart both rear drums, and all the brake hardware, unbolt the lever, and bolt up the new assembly (complete with new pivot pin and e-clip).
BUT FIRST make sure that this is the actual issue. Lay down under the truck, and on the back of the drum, towards the rear of the truck you will find the e-brake cable. Follow this to the backing plate where it connects to the lever. Try moving it by hand or a flat head screwdriver. If it doesnt move with a little effort, it is frozen and the above procedure will remedy it.