First, check the fluid. If it is low, the pressure won't be high enough in the system to turn the wheels at idle. Also, remember that moving makes the wheels easier for the system to turn so to clarify, are you moving and at idle or stopped when this issue occurs?
the ps fluid was a little low. i put enough in to get it between the two lines. didn't help.
it was suggested that the belt might be slipping and i should spray on some belt treatment. the next guy said that won't help. he suggested that the belt needs tightening and there is an adjustment that can be made. if the tightner is all the way to the end then i need a new belt, he said. that's where i'm at.
I would think you would hear the belt slipping if it were that loose. How many miles are on the car? I am not sure about STS but some of my other cars have had adjusting screws on the steering gear for pressure adjustment. Sounds like it needs to go to the dealership; either a pump or a gear. Is it leaking PS fluid anywhere? On the bright side, I can't imagine a situation where you would need to turn if you weren't moving!
Dick62M ,I advise owners get some sort of extended warranty for their Cadillac because with all the gadgets I know some will fail during your tenture .I had my 05 1SG for a year and it's been back to the dealer about 7 times under warranty of course so I'm speaking from experience and now it has to go back again for a new leftside headlight composite due to moisture retention and by the way my steering rack was replaced too. Good luck and please heed my warning and please purchase a warranty.and:welcome: