GM-GMC: 92 Chevy Truck, -no signals, chevy truck, realys

Question
Brake lights ok, No turning signals. Ohmed out the connections under the dash ( on the steering column) and got a signal. So the turning switch is ok. I turned the light switch on, volt meter on the other end of connection and got a 12 v signal across the Bl and lt bl wires. But when I volt meter the fuse insert with key on there is no 12V at the fuse. Does it sound like a burnt hot wire ??
Had trouble in the past when running the boat trailer. Rewired the trailer with a solid 16 awg wire. last outing all lights on truck and trailer worked fine. Next day turn signals out again. It seems to be a reoccuring problem. Bulbs and fuse ok .  Fan switch quit working too, fan motor is ok, these two dont share any realys do they ??  Thanks a million !!!!!!!!!!!!!!!!!!!!!!1

Answer
Those two system are independant of each other.  As for you trailer wiring double check the plug, and any other connectors at the rear of your vehicle.  It takes very little corrosion to complete the circuit and cause funny things to happen.
Unfortunately I cannot access the wiring diagrams for that particular vehicle online, they are hard copy only. Check your feeds/grounds and outputs right at the base of the steering column but use a test light.  A test light will light nice and bright or dim.  A meter would show 12v for both.
You seem to be on the right track, I cannot give you a sure thing fix for something like this, only suggestions or a logic sequence of things to check.  My gut reaction is still a trailer or corroded wiring connector issue.  Good luck, let me know how you make out.  One more thing to check is the flasher module, if that truck is equipped with one change it. They are cheap only a couple bucks.  That could be causing your problem also.