[Andice]

GMCNut: I agree with rest of the comments posted so far: check the turn signal switch. While the GMC switches seem to be a better design than the Chevy version, they are prone to getting dirty and if they ever get hot they cause small grooves to be melted in the plastic right near or at the contacts inside the switch. A good cleaning and possibly some light sanding or dremel tool work can smooth out these melted grooves, thus allowing the contacts to do what they are supposed to do. You'll have to remove the steering wheel. You will also have to be careful not to lose any of the upper column bearings when you remove the signal switch from the column. This is also a good time to clean the horn contacts. Test it before you reinstall the wheel. Good luck.