My brakes and power-steering are not working. The brake pedal is hard, but the brakes will not engage. The power steering was not working at the same time. It has brake fluid, but when I took the power steering cap off, while truck was off, it popped fluid out the top, even-though the truck was cold. The brakes are now working better but I can still feel them not catching, like their is air in the system. This problem happened without warning. It sat overnight and when I went to leave in the morning I found I couldn't stop or turn. I believe I'm getting air in the system somehow, but I have never heard of the Brakes and Steering operating off the same system pump. Where could air be getting into both systems from, and how do I fix it.

Yes, your brakes are boosted by the power steering pump rather than by vacuum. I don't think it's air in the system. More likely your pump has failed, but you can try bleeding the pump. Here is a procedure from autozone.com:

Observe the following:
Use clean, new power steering fluid type only Hoses touching the frame, body or engine may cause system noise. Verify that the hoses do not touch any other part of the vehicle. Loose connections may not leak, but could allow air into the steering system. Verify that all hose connections are tight.


NOTE Power steering fluid level must be maintained throughout bleed procedure.

1. Fill pump reservoir with fluid to minimum system level, FULL COLD level, or middle of hash mark on cap stick fluid level indicator.
   NOTE With hydro-boost only, the oil level will appear falsely high if the hydro-boost accumulator is not fully charged. Do not apply the brake pedal with the engine OFF . This will discharge the hydro-boost accumulator.
   
2. If equipped with hydro-boost, fully charge the hydro-boost accumulator using the following procedure:
   1. Start the engine.
   2. Firmly apply the brake pedal 10-15 times.
   3. Turn the engine OFF
   
   
3. Raise the vehicle until the front wheels are off the ground.
4. With key in the ON position and the engine OFF , turn the steering wheel from stop to stop 12 times. Vehicles equipped with hydro-boost systems or longer length power steering hoses may require turns up to 15 to 20 stop to stops.
5. Verify power steering fluid level per operating specification.
6. Start the engine. Rotate steering wheel from left to right. Check for sign of cavitation or fluid aeration (pump noise/whining).
7. Verify the fluid level. Repeat the bleed procedure if necessary.

1. Fill pump reservoir with fluid to minimum system level, FULL COLD level, or middle of hash mark on cap stick fluid level indicator.
   NOTE With hydro-boost only, the oil level will appear falsely high if the hydro-boost accumulator is not fully charged. Do not apply the brake pedal with the engine OFF . This will discharge the hydro-boost accumulator.
   
2. If equipped with hydro-boost, fully charge the hydro-boost accumulator using the following procedure:
   1. Start the engine.
   2. Firmly apply the brake pedal 10-15 times.
   3. Turn the engine OFF
   
   
3. Raise the vehicle until the front wheels are off the ground.
4. With key in the ON position and the engine OFF , turn the steering wheel from stop to stop 12 times. Vehicles equipped with hydro-boost systems or longer length power steering hoses may require turns up to 15 to 20 stop to stops.
5. Verify power steering fluid level per operating specification.
6. Start the engine. Rotate steering wheel from left to right. Check for sign of cavitation or fluid aeration (pump noise/whining).
7. Verify the fluid level. Repeat the bleed procedure if necessary.