I have a '67 c10 automatic column in my '65 Chevy c10, the plug for the column is a little different. I matched all the colors with one another assuming that nothing really changed. When I hit the brakes both of my turn signal lights on my dash come on and my park lights come on. I replaced the turn signal switch and the flasher on the fuse box, I can't get my turn signals to work or my parking lights to come on with the lights. I've gone through the wires and fuse box and can't find anything wrong.
this one is a bit shorter, and might also help. http://www.jalopyjournal.com/forum/threads/tech-gm-turn-signal-wire-colors.124217/ .
Are you using a turn signal wired for a 65 or the 67 turn signal? Pretty sure the 67s had a separate t.s. bulb so you would need to take that into account.
67 only had one bulb in back for stop/turn on each side. Pretty hard to guess what's wrong here....did all the colors on the turn signal switch match up exactly? sounds like maybe white is connected to yellow, or something? or maybe there's wiring issues at the front of the truck? or the dash cluster is funky? maybe purple is going somewhere it shouldn't? maybe pictures?
Wasn't '67 the first year for emergency flashers? Not sure when the trucks were so equiped. Could be some extra wires there and I think that is when they started using the two flashers also. May have to wring it out with an ohm meter. D
Unplug your switch and with an ohm meter find the three wires that have continuity with each other. One will be the brake switch feed and the other two are the rear brake lights. Now switch the left turn signal on and the one wire of the three that looses continuing is your left rear turn signal. Now switch it to the right and the one of the three that looses continuity is your right rear turn and the remaining wire will be the brake light switch. With it switched to the right find the other wires that now have continuity with the right rear wire. These will be the right front turn signal and the turn signal flasher wires. Now switch left and find the two wires that have continuity with the left rear. The wire that had continuity with the others in both left and right is the turn flasher wire and the others are front turn signals respectively. The other two wires are the horn relay ground wire and hazard flasher wire if so equipt. If you only have one indicator light it will come off of the three prong flasher, if you have individual left and right indicators they will come off of the front turn signal wires. If you have more questions post them here or PM me. I hope this helps