Ok have seen a few older threads here for this problem, but hoping some of you here have had and fixed the same problem.

Left turn signal will work when head lights are off, but dash lights to include radio/dvd player will also blink, the same with the exterior lights (signal and parking). However when the head lights are turned on the front and rear left signal light will remain illuminated (yellow) outside and on the dash as well and will not blink. The right signal is fine all the time.

Have changed bulbs, with the correct ones I might add. No corrossion or wire problems I can see. Also do have a trailer wire harness which looks to be fine. I had it installed when i bought the car (used 2 years ago) and had no problems until now. All fuses are good and I would assume the relay is fine since the right signal functions properly, but haven't pulled it to test or check it.

Have seen suggestions that I should check tow harness for corrosion or disconnect it all together; look for rub or cut spots on the left signal wire, look for corrossion at bulb sockets and that the contacts in the signal stalk/lever might have worn.

This just started to happen about a month ago.

Would appreciate insight to the problem/solution from others.
Thanks

I want to say from memory from different forums that the problem might either lie in the multifunction switch (the one to the left of the steering wheel with the headlight switch and all) or the flasher.