On my drive home from work tonight I noticed my blinker doing something odd. When I turn on my right blinker, it works normally. When I turn on my left blinker it just stays solid. The light on the dash and the turn signal light on the left side of the car just stays solid.

What is causing this? I have been driving all day and it didn't do this until now.

 

check for any turn signal bulbs burnt out? front and back.

 

Yep sounds like a burnt out bulb to me...

 

I would third the burnt bulb, and while your checking those you might as well clean your bulb sockets and use a little grease to prevent oxidation.

 

Be sure to use dielectric grease. Normal axle grease can dry out, which will then allow the socket to attract moisture.

 

And on the off chance it's not the bulb, chances are it's the flasher. If I'm not mistaken, putting the four ways on should make everything operate "normal", meaning your signal shouldn't stay solid until the flashers are turned off.

 

It's a burnt out bulb or defective socket. The flasher is designed to stop flashing if a bulb is burnt out as an indication of such. Don't replace the flasher with a digital one or you will lose that feature and you won't know when a bulb is burnt out.

 

I changed both bulbs yesterday, the parking light/turn signal light, they both work... The sockets are not defective. Next thing I am trying to check is the turn signal switch, but that doesn't make sense to me only because the right side still works.

 

Actually it is possible to be a defective turn switch. The turn switch has separate contacts for the left and right side and for the front and rear (4 total). Anything in the circuit path at the front or rear on the side that has the problem is suspect, including wiring, connectors, and DRL module (if installed as option T61).
It is just much, much more common to be a defective bulb or socket.

 

Be sure you clean the bulb contacts, don't JUST replace bulbs, and always use a thin amount of dielectric grease to help prevent corrosion...