Toyota Repair: Turn signal problems on 98 Tacoma, left turn signal, side marker

Question
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Followup To
Question -
I'm having a problem with my signal lights, in that the right hand turn signal remains on when the head lights are on, and the turn signals aren't functioning properly.

In general;
Headlights off:
Left turn signal works properly, but front side marker light not flashing.
Right turn signal works, but left hand side marker and tail light flashing dimly as well.

Headlights on:
Left turn signal works properly, but right hand signal lights remain solid.
Right turn signal has no effect.

I've checked all of my fuses and bulbs, and couldn't find a problem.  

The local dealership had my truck for 2 hours and told me nothing except that I owed them $180.  If you can think of any likely causes for this and means of checking for them, it would help me out a lot.  

Thanks,
Jeff

PS - the ABS light came on briefly some time ago while I was driving, but turned off when I stopped my truck and has not come on since.  Not sure if this is possibly related.

Answer -
I don't understand why you would owe them any money if they didn't fix anything and can't tell you what the problem is, I wouldn't pay them a dime.
A few questions I need to have an answer for before I can help:
Has the truck been in an accident?
Have any repairs been attempted to fix this problem and what were they?
I understand that you checked all the bulbs but if the wrong bulbs are installed in any of the sockets, even in the tail or stop lights it may cause this problem.
Does the truck have a trailer hitch and is it toyota factory installed or aftermarket(this is important).
Please answer these questions and I might be able to help.

I checked all of the bulbs against the manual I have, and they are all correct.  I do have a trailer hitch, and it is an aftermarket hitch.

Answer
Try disconnecting the trailer wiring from the tailight wiring, you may have to remove the tailights or there may be a connector underneath, one way or another completely disconnect the wiring and see if the electrical problem stops, I have a feeling this is the problem.