There is a vacuum attachment on the power brake booster. If there is a vacuum leak this part could be causing the brakes to be hard, or this part could be the vacuum leak. The steering could also be vacuum assisted occurring from the same source.
Are there any other symptoms (i.e. vent/floor/defrost not blowing air or changing properly)?
For several years of the Chevy astro van had a power brake and power steering system that was linked together. Instead of a brake booster, the power steering pump provides power to the power brake system. Often, if the brake pedal would become hard to push, it is a power steering pump problem. Change the power steering pump and the power steering fluid and your problem may disappear.
you steering wheel starts shaking because you probably have warped roders your shaking will get worse at higher speeds and when pressing the brake
Are the brakes out or is the power brake system not working properly. I believe those vehicles have the hydro boost power brake system. If so, the power steering pump is what applies the power brakes, no vacuum is needed. If something is wrong with the power steering pump (empty, no belt, malfunctioning) it will affect the power brakes as well.
It sounds as if you have an electrical problem that needs to be checked. You may even have the wrong fuse for your brake lights.
Power steering pump failure, has power brake assist line conected to it. It uses the power steering pump to bring hydraulic pressure to master cylinder.
Check bulbs they are double filamented with smaller for brake lights Could be a problem in steering column
It is probably your brake booster located on the firewall.
You could be pressing the brake pedal too hard. Another reason why it may jerk is because the pull brake is engaged.
Try moving the steering wheel at same time If moving the steering wheel does not work, it is likely a problem with the Brake/Shift Interlock switch located at the brake pedal lever. It maybe that a wire is broken or, the switch is bad. I had this problem with a 1997. The brake light fuse was blown because of a trailer. With the brake fuse blown, it would not come out of Park.
Bulbs? Sockets? Steering column switch?
Probably brake pads.
Blown fuse? Bad stoplight switch? Open wire to brake lights Not ground at brake light sockets? Problem in steering column (turn signal circuitry)?