1990 Mercury Marquis emergency brake

On a 90 the most likley cause is frozen cables, disc or drum in the rear?

Thanks. Car is equipped with all disk brakes.

Grab a large screwdriver or a prybar, try pulling back on the lever on the back of the caliper to release the parking brakes. Then determine which cables is sticking by pulling on them by hand, the one that doesnt return needs to go!

I am sorry to say I made a typo! In the box I clicked the wrong year: It is an Mercury Grand Marquise 2000 !!!! ( I wondered about the question : Drum or Disc. 2000 came with all disc only).

Right, and not connected to the caliper either in 2000, so tug with your hands rearward to get some slack, the replace the frozen or sticking cable.