One problem related to power steering pump has been reported for the 2004 Cadillac DTS. The most recently reported issues are listed below.
During rainy periods while driving at a slow speed (20-30 mph) in parking lots or residential streets where water has pooled when I hit a deep (3-5 inches) puddle the power steering on my 2004 Cadillac deville Dts stops functioning for a period of 30-45 seconds. Because I am unable to steer my car I must come to a complete stop until the power steering recovers. I have taken my car to the dealer when it was under warranty and now to a repair shop several times to have the vehicle inspected and repaired. All tell me there is nothing they can do. Water is splashing onto the engine belt that turns the power steering pump and that there is nothing that can be done without some sort of factory modification such as a splash guard to prevent the water from splashing onto the drive belt.