The combination and turn signal switch is the lever that is typically situated on the left side of the steering column and controls the turn signals, exterior, and/or interior lighting. Depending on your specific vehicle, some of those functions might be elsewhere, or there could be even more functions on your switch. Usually, a switch includes the stalk (portion that sticks out from the steering column) and the mounting area (usually a ring or flat plastic bracket that bolts to the column). On the mounting area, there are some wires and a plug for the harness to connect to it. The turn signal function is standard for basically all vehicles sold in the last decade. Push it down for a left turn signal and pull it up for right turn signal. If you think about the direction you rotate the steering wheel, the signal moves in the same direction as the steering wheel rotation. Another basic function of this switch is the headlights. It varies from car to car, but on many of them, the headlight switch is at the very end of the stalk. The tip rotates forward or backward to select the different settings. There's OFF, of course, and then PARKING LIGHTS or RUNNING LIGHTS (these are the typically the turn signals, or another amber light in the front left on steady). The parking light setting should only be used when the vehicle is parked so as to illuminate the vehicle's surroundings, especially in dark areas. Another function that may be on your switch is the fog lights. As the name implies, these are used during foggy conditions and they're designed to brightly illuminate the ground just in front of you. Their function is a simple on and off. Yet another function you may have is for the instrument illumination. Generally, this is a gradual setting to make the instrument lighting bright, dim, or anywhere in between.
The most common problem you're likely to have with the turn signal switch is a failure of one of the above mentioned functions. The switch could stop working because of a shorted wire, or a contact in the switch is no longer making its connection. Or, it could be that the movement of certain functions gets stuck or doesn't stay in one position anymore. The second largest issue is with the turn signal cam. This is the part inside the steering column that holds the turn signal in the up or down position until a turn is made and then it auto cancels the turn signal stalk. This part is plastic and is prone to breaking after it gets old. There shouldn't be any danger if these functions stop working, but it could be a nuisance for other drivers if you're unable to tell them when you're going to turn. It's best to have this fixed as soon as possible.
To install the turn signal switch, you'll need to disassemble the steering column shroud. There could be a number of ways it's installed depending on the vehicle. You can either consult a repair manual for your specific vehicle, or take it to a certified mechanic.
With a properly functioning turn signal switch, you'll no longer be the person that "doesn't know where their turn signal is" and can continue to control the majority of the lighting functions on your vehicle. Car Parts Discount has a wide variety of turn signal and combination switches for many cars and trucks at low prices.