soba_03,
It might help with future posts if you update your profile to show what kind of truck you have.
Researching your previous posts leads me to believe that the rig in question is a '61 Suburban. You have done lots of good troubleshooting hunting for this gremlin, but it could be in your turn signal switch proper.
The '6066 GMC' site shows wire color and connector location for a '61 GMC, but I don't know if Chevy is the same. My idea would be to pull the connector at the base of the column and check the appropriate color wire with a meter. This takes short and grounds out of the equation and focuses on the switch proper.
The site I mentioned calls out DARK/BLUE for RtFrnt turn signal and LT/BLUE for LftFrnt turn signal. With the connector pulled apart, and your meter attached, each wire should energize separately when you flip the turn signal lever. If both come on, you have found the problem.
Google '6066' and you will find the site and lots of great info.
Stuart
