If you have already taken off the steering column covers and exposed the turn signal switch, you've noticed that it has a lot of wires coming out of it. In fact, there are about 23 wires coming out of the turn signal switch (depending on whether you vehicle is equipped with cruise control or not).
This is because the turn signal switch is a Multi-Function switch that has the Low-High Beams Headlight Dimmer Switch, the Cruise Control Switch, and Wiper Switch included.
Since the turn signal switch isn't cheap (at your local auto parts store expect to pay about $150 US)... it's best to test it and make sure it's really BAD. In this article, I'll show you how to test it yourself.
IMPORTANT: You will to disconnect the turn signal switch's connectors from the instrument panel harness connector... and this will require that you disable the air bag system on your GM vehicle (know as SIR).