Troubleshooting rack and pinion steering systems. Most modern cars use power steering systems comprising of a power steering pump, hosing, and either a rack and pinion steering or a power steering gear box. When you are having problems with your steering system, it is most likely going to be due to a problem with the fluid in the hydraulic system. If you have a leak, your fluid level will get low and possibly introduce air into the system. If this is the case, you will get a jerky or vibrating feel through the steering wheel when you attempt to steer the car. If the fluid level is low, it could also result in a humming or whining sound as the pump is no longer receiving appropriate lubrication which it relies on the fluid for under normal operating conditions. If the power steering rack itself has a problem, you might find that part way through the steering motion, you get binding, or loose, the steering wheel itself feels loose in your hands. This often times is an indication that there is excessive wear on one of the gears in the power steering rack. Some power steering racks can be adjusted while others cannot. If the power steering level is low, obviously the solution for that is to simply top off level and see if the problem goes away. If you are losing power steering fluid on a regular basis, you will obviously want to find where the leak is coming from, and most likely it's either going to be from one of the hoses or from one of the seals on the power steering rack itself.