The parking brake may not release automatically due to a failed vacuum switch or actuator. Our technicians tell us that if vacuum is supplied to the actuator when the transmission is in gear, the vacuum switch is functioning and replacing the actuator should correct this concern.Google+
Car Problem Reports
Cadillac Seville SLS Vacuum Brake Release Switch Can Fail
Cadillac Seville SLS Problem
Visitor, 1996 Cadillac Seville SLS, 126,000 mi
Worked fine (I use the park break all the time) until & got the car out of the shop "new transmission" put in. I was thinking that they didn't contact a cable when the transmission was dropped & replaced; however doesn't run on a cable; its a vacuum line, have to take back to shop to see if a vacuum hose loose or disconnected when they were working on the transmission. Unresolved currently.