Toyota Repair: Problem with turn signal on a 97 Tacoma: Follow up, turn signal switch, left turn signal

Question
OK, is there any way to tell if it definitly is NOT the combination switch? (they are pretty darn expensive) Upon checking the wires from the switch in the steering wheel I found that there is no juice flowing into the switch. Does that help narrow it down at all? So if it's not the combination switch then all things point to the trailer hitch system. I do remember buying a special box for the trailer harness (b/c of the separate turn signal hookups

Do the trailer lights have a wiring harness for that I can just disconnect to help with determining the problem.


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Followup To

Question -
I have a 97 Tacoma. The left turn signal suddenly stopped working in the front, and the rear left turn signal flashes very fast. The right side works fine. I tried replacing the bulb, but that didn't help. I bought a new flasher but can't find the darn thing under the dash. Although I do hear it flashing at that high rate. A knowledgeable friend of mine says that it's the Turn Signal Multi-Function Assembly (turn signal switch). Which of course is very expensive and I don't want to replace it if I don't have to.
The truck also has an aftermarket trailer light system which I heard can give problems, but I don't know how that would effect the front turn signal like that.  Which is the most likely cause or scenario, what would you recommend doing?



Answer -
First make sure that the wire harness is connected to the turn signal socket, if it is and the bulb is good then I would suspect the trailer wiring, I don't think I have ever replaced a flasher unit in a toyota in over 20 years so i really doubt if that's the problem, probably not the combination switch either, try disconnecting the trailer harness completely from the rest of the system and I believe the problem will disappear.

Answer
Since all but the left turn signal in the front are working there must be 12 volts to the turn signal switch, there is only one fuse supplying the switch with voltage, it's not a fuse, it's a wiring problem, remove the tail lights and disconnnect any wires that are spliced into the factory wiring harness, disconnect or cut the wires for the converter box, I'm sure that if you eliminate the trailer wires that you will solve the problem.