How do you change fluid in power steering system

Question edited for clarity and dreadful spelling of 'Cadillac'.
Question moved to model category.

Yes it does have power steering.

https://www.google.com/search?q=2009+Cadillac+DTS+power+steering

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Causes of Power Steering to fail.

• Contamination problems occur more frequently in rack and pinion power steering systems. Contamination can occur when pumps fail, hoses deteriorate, or moisture gets into the power steering fluid. All of these problems result in material contaminating the power steering fluid which can plug small orifices in the steering system, increase friction, and interfere with the fluids hydraulic characteristics, resulting in a failure of the power steering system.

Low fluid

• Low power steering fluid levels reduce the amount of hydraulic pressure created by the power steering pump, resulting in hard steering. Low fluid levels also cause increased wear of the power steering pump from inadequate lubrication and high fluid temperatures which further accelerates pump wear. Low power steering fluid can cause a power steering pump to wear out prematurely and can result in the eventual failure of the power steering system if not corrected.

Snapped belt

• Many vehicles use power steering pumps which are driven by a belt connected to the crankshaft of the engine. Worn belts can slip causing a reduction in the fluid pressure produced by the power steering pump, which increases the effort needed to operate the steering system. Power steering belts that catastrophically cause an immediate loss of power steering as the pump is no longer being driven by the engine.

Worn pump

• As power steering pumps are operated and age they wear out. The seals and internal parts of the power steering pump break down over time and lead to an incremental loss of fluid pressure. As the pump wears out, pump noise and steering effort increases. Worn out pumps will eventually fail, leading to a total loss of fluid pressure and a failure of the power steering system.

Leaks

• Power steering systems require hydraulic fluid to operate. Hydraulic power steering fluid can leak from worn or damaged hoses and failing seals. When enough fluid is lost, the power steering pump can overheat or wear out prematurely, resulting in a loss of hydraulic pressure and failure of the power steering system.

If you can't find a power steering fluid reservoir under the hood in the engine compartment your G6 could have Electronic Power Steering . If you look up under the dash below the steering column you will see a electric motor mounted to the steering column !
The power steering system reduces the amount of effort needed to steer the vehicle. The system uses the powertrain control module (PCM), body control module (BCM), power steering control module (PSCM), discrete battery voltage supply circuit, steering shaft torque sensor, steering wheel position sensor, power steering motor, driver information center (DIC), and the serial data circuit to perform the system functions. The PSCM and the power steering motor are serviced as an assembly and are serviced separately from the steering column assembly. The steering shaft torque sensor and the steering wheel position sensor are not serviced separately from each other or from the steering column assembly. The steering column assembly does not include the power steering motor and module assembly.

http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f80cb3bdbFollow your power steering hoses to your steering and disconnect and use a container to catch fluid,you can also loosen hoses at pump and put towel over hole and blow out line to get all fluid out,make sure when you blow , the other end is secure and fluid doesn't go every where,good to have another person helping.Here's a link on how to bleed.

Power steering fluid has not been changed in eons, i suggest draining the fluid, refilling with a cheap fresh fluid, then bleed the system by turning the wheels from lock to lock a few times with the cap of the steering fluid master cylinder off, then drain the system again & refill with good quality power steering fluid - it should be pink & smell sweet, - the power steering fluid that is!!

It's a bit difficult to do with out making a mess, you need to loosen the power steering hose and let the fluid run out, Then tighten it and refill the fluid, you will only be able to change about 90% of the fluid.

Some garages have electric pump systems that can completely change the fluid but this can be expensive depending on the garage.

Power steering fluid comes in two colors, one of which is amber and the other color is a pink/red combination. When power steering fluid becomes much darker than when it is new, that means it is time to change it. Some vehicles have a light brown power steering fluid. just change the fluid and go from there ! use a turkey baster to remove fluid in power steering pump. refill the pump with new fluid, make sure air is out of system. you may need to bleed system when done. there will be some old fluid in system. but this is ok. to get air from system, just jackup front of car. move steering wheel from left stop to the right stop. do this a few times and be sure fluid is up in tank.

YOU HAVE AIR IN THE POWER STEERING SYSTEM.YOU NEED TO BLEED POWER STEERING PUMP FIRST BEFORE DRIVING VECHICLE.CHECK POWER STEERING FLUID LEVEL ADD MORE POWER STEERING UNTIL REACH FULL COLD MARK..RAISE VECHICLE FRONT WHEELS OFF THE GROUND.START ENGINE LET IT IDLE WHILE TURNING STEERING WHEEL LEFT TO RIGHT NON STOP DONT LOCK OR STOP STEERING WHEEL KEEP TURNING IT SEVERAL TIMES CHECK POWER STEERING FLUID IF LOW ADD UNTIL YOU GET COLD MARK ON DIP STICK DONT OVER FILL POWER STEERING PUMP BLOW A SEAL.IF POWER STEERING FLUID LOOK TAN COLOR SYSTEM FULL OF AIR.TURN OFF IGNITION LET CAR SET FOR A WHILE CHECK FLUID LEVEL.IF STEERING WHEEL FEEL STIFF HARD TURNING DONT DRIVE CAR UNTIL YOU HAVE NORMAL STEERING.IF STILL HAVE AIR IN SYSTEM BLEED SYSTEM UNTIL AIR IS OUT.

Power steering flush can't hurt. In fact flushing the power steering systems on some vehicles has solved power steering issues. Power steering fluid is one of the few fluids that is not filtered. Yet it is subject to contamination, heat cycles, shearing, and compression just like many of the other fluids in your car.

Unless there is a problem with the fuel injection system a service is not needed.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

you changed all the oils and fluids. uumm theres really not much you can do when it comes to that check the belt and if thats not it get a new pump