Take the connecting wire off the battery terminal that's negative, and turn off the audio system's anti-theft feature if your car has one. Take out the airbag control system first, then remove the steering wheel and its covering. Take the electrical connection off the turn signal and headlight switches. Using an ohmmeter, check the continuity of the switch terminals: Taking off the switch cover and steering wheel, the test must show three different connections: no connections should happen when the stalk is centered, one connection should be across terminals 1 and 2 when turning left, and one connection should be across terminals 2 and 3 when turning right. If the switch doesn't operate, replace it. To replace the switch, first take out its screws, then disconnect it from the switch body. Reinstallation goes the other way, just make sure the spiral cable is centered before you put back the steering wheel.