The high-pressure power steering lines are known to leak.Google+
Car Problem Reports
Cadillac Seville STS High Pressure Power Steering Hose Can Leak Fluid
Cadillac Seville STS Problem
Average Mileage: 111,141 mi (70,000 mi - 200,000 mi)
Visitor, 1994 Cadillac Seville STS, 103,565 mi
Had a leak in the high presure side of the power streering, was leaking and the Dealer said the line had to be changed at $200.00 plus for the part and labor. Took it to a regular shop that I use. He got what he needed at NAPA for $60.00 and I got it fixed for a little over $100.00. I have found that most of the issues can be fixed by regular Auto repair shops.
Visitor, 1994 Cadillac Seville STS, 200,000 mi
My car all of a sudden had no power steering, and after verifying that the pump still seemed to work, I'm assuming that the hose is bad as well. I really don't know though and am still looking. Powersteering makes a really loud noise when I turn the wheel and the car is not keeping the power steering fluid.
Had to replace high pressure hose.
Visitor, 1999 Cadillac Seville STS, 71,000 mi
Experiencing this issue now, replacing the line soon.