Toyota Repair: tacoma turn signals, left turn signal, turn signals

Question
QUESTION: i have an 04 toyota tacoma. recently my left turn signal started to stick when i turn my parking lights or headlights on. it works fine when the headlights are off. occasionally both taillights will blink with the turnsignal on. any idea what might cause this?

ANSWER: Was anything done recently, any bulbs replaced or any electrical components replaced, does it have a trailer hitch?

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QUESTION: nothing was done recently but it does have a trailer hitch. should i disconnect the trailer wiring and see if this corrects the problem?

Answer
Yes, that was going to be my next step, I have seen too many problems like this caused by trailer hitch wiring, in most cases the converter box is the problem. By the way is it factory installed or aftermarket, let me know after disconnecting the wiring and see if it fixes it.